Circular prime

Circular prime
	The numbers generated by cyclically permuting the digits of 19937. The first digit is removed and readded at the right side of the remaining string of digits. This process is repeated until the starting number is reached again. Since all intermediate numbers generated by this process are prime, 19937 is a circular prime.
Named after	Circle
Publication year	2004
Author of publication	Darling, D. J.
No. of known terms	27
First terms	2, 3, 5, 7, 11, 13, 17, 37, 79, 113, 197, 199
Largest known term	(10^270343-1)/9
OEIS index	A016114; Circular primes (numbers that remain prime under cyclic shifts of digits);

A circular prime is a prime number with the property that the number generated at each intermediate step when cyclically permuting its (base 10) digits will be prime.[1][2] For example, 1193 is a circular prime, since 1931, 9311 and 3119 all are also prime.[3] A circular prime with at least two digits can only consist of combinations of the digits 1, 3, 7 or 9, because having 0, 2, 4, 6 or 8 as the last digit makes the number divisible by 2, and having 0 or 5 as the last digit makes it divisible by 5.[4] The complete listing of the smallest representative prime from all known cycles of circular primes (The single-digit primes and repunits are the only members of their respective cycles) is 2, 3, 5, 7, R₂, 13, 17, 37, 79, 113, 197, 199, 337, 1193, 3779, 11939, 19937, 193939, 199933, R₁₉, R₂₃, R₃₁₇, R₁₀₃₁, R₄₉₀₈₁, R₈₆₄₅₃, R₁₀₉₂₉₇, and R₂₇₀₃₄₃, where R_n is a repunit prime with n digits. There are no other circular primes up to 10²³.[3] A type of prime related to the circular primes are the permutable primes, which are a subset of the circular primes (every permutable prime is also a circular prime, but not necessarily vice versa).[3]

Other bases

The complete listing of the smallest representative prime from all known cycles of circular primes in base 12 is (using inverted two and three for ten and eleven, respectively)

2, 3, 5, 7, Ɛ, R₂, 15, 57, 5Ɛ, R₃, 117, 11Ɛ, 175, 1Ɛ7, 157Ɛ, 555Ɛ, R₅, 115Ɛ77, R₁₇, R₈₁, R₉₁, R₂₂₅, R₂₅₅, R_4ᘔ5, R₅₇₇₇, R_879Ɛ, R_198Ɛ1, R₂₃₁₇₅, and R₃₁₁₄₀₇.

where R_n is a repunit prime in base 12 with n digits. There are no other circular primes in base 12 up to 12¹².

In base 2, only Mersenne primes can be circular primes, since any 0 permuted to the one's place results in an even number.

References

The Universal Book of Mathematics, Darling, David J., p. 70, retrieved 25 July 2010
Prime Numbers—The Most Mysterious Figures in Math, Wells, D., p. 47 (page 28 of the book), retrieved 27 July 2010
Circular Primes, Patrick De Geest, retrieved 25 July 2010
The mathematics of Oz: mental gymnastics from beyond the edge, Pickover, Clifford A., p. 330, retrieved 9 March 2011

External links

Circular prime at The Prime Glossary
Circular prime at World of Numbers
OEIS sequence A068652 a related sequence (the circular primes are a subsequence of this one)
Circular, Permutable, Truncatable and Deletable Primes

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[The_Universal_Book_of_Mathematics-1] The Universal Book of Mathematics, Darling, David J., p. 70, retrieved 25 July 2010

[Prime_Numbers_-_The_Most_Mysterious_Figures_in_Math-2] Prime Numbers—The Most Mysterious Figures in Math, Wells, D., p. 47 (page 28 of the book), retrieved 27 July 2010

[Circular_primes-3] Circular Primes, Patrick De Geest, retrieved 25 July 2010

[The_mathematics_of_Oz:_mental_gymnastics_from_beyond_the_edge-4] The mathematics of Oz: mental gymnastics from beyond the edge, Pickover, Clifford A., p. 330, retrieved 9 March 2011

Prime number classes
By formula	Fermat ( $2 2 n + 1$ ) Mersenne ( $2 p - 1$ ) Double Mersenne ( $2 2 p -1 - 1$ ) Wagstaff $(2 p + 1)/3$ Proth ( $k \cdot2 n + 1$ ) Factorial ( $n! \pm 1$ ) Primorial ( $p n # \pm 1$ ) Euclid ( $p n # + 1$ ) Pythagorean ( $4 n + 1$ ) Pierpont ( $2 m \cdot3 n + 1$ ) Quartan ( $x 4 + y 4$ ) Solinas ( $2 m \pm 2 n \pm 1$ ) Cullen ( $n \cdot2 n + 1$ ) Woodall ( $n \cdot2 n - 1$ ) Cuban ( $x 3 - y 3)/(x - y$ ) Carol $(2 n - 1) 2 - 2$ Kynea $(2 n + 1) 2 - 2$ Leyland ( $x y + y x$ ) Thabit ( $3\cdot2 n - 1$ ) Williams ( $(b -1)\cdot b n - 1$ ) Mills ( $⌊ A 3 n ⌋$ )
By integer sequence	Fibonacci Lucas Pell Newman–Shanks–Williams Perrin Partitions Bell Motzkin
By property	Wieferich (pair) Wall–Sun–Sun Wolstenholme Wilson Lucky Fortunate Ramanujan Pillai Regular Strong Stern Supersingular (elliptic curve) Supersingular (moonshine theory) Good Super Higgs Highly cototient
Base-dependent	Palindromic Emirp Repunit $(10 n - 1)/9$ Permutable Circular Truncatable Minimal Weakly Primeval Full reptend Unique Happy Self Smarandache–Wellin Strobogrammatic Dihedral Tetradic
Patterns	Twin ( $p, p + 2$ ) Bi-twin chain ( $n - 1, n + 1, 2 n - 1, 2 n + 1, \dots$ ) Triplet ( $p, p + 2 or p + 4, p + 6$ ) Quadruplet ( $p, p + 2, p + 6, p + 8$ ) k−Tuple Cousin ( $p, p + 4$ ) Sexy ( $p, p + 6$ ) Chen Sophie Germain/Safe ( $p, 2 p + 1$ ) Cunningham ( $p, 2 p \pm 1, 4 p \pm 3, 8 p \pm 7, ...$ ) Arithmetic progression ( $p + a\cdotn, n = 0, 1, 2, 3, ...$ ) Balanced ( $consecutive p - n, p, p + n$ )
By size	Titanic (1,000+ digits) Gigantic (10,000+ digits) Mega (1,000,000+ digits) Largest known
Complex numbers	Eisenstein prime Gaussian prime
Composite numbers	Pseudoprime Catalan Elliptic Euler Euler–Jacobi Fermat Frobenius Lucas Somer–Lucas Strong Carmichael number Almost prime Semiprime Interprime Pernicious
Related topics	Probable prime Industrial-grade prime Illegal prime Formula for primes Prime gap
First 60 primes	2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229 233 239 241 251 257 263 269 271 277 281
List of prime numbers