A107645 Numbers k such that the string 1311k is the decimal expansion of a prime number.

11, 13, 29, 43, 49, 71, 103, 109, 127, 131, 143, 173, 181, 217, 223, 229, 239, 241, 251, 259, 263, 287, 301, 307, 311, 341, 353, 367, 377, 383, 403, 407, 419, 433, 449, 473, 481, 493, 503, 509, 523, 547, 553, 559, 577, 599, 617, 619, 623, 643, 689, 691

Offset

1,1

Comments

11 and 13 are twin primes.

Links

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Example

k=71: 131171 is prime.
k=131: 1311131 is prime.

Prog

(Magma) [ n: n in [1..800] | IsPrime(Seqint(Intseq(n) cat [1, 1, 3, 1])) ];

Crossrefs

Sequence in context: A115560 A045466 A158759 * A106014 A261371 A289490

Adjacent sequences: A107642 A107643 A107644 * A107646 A107647 A107648

Keyword

nonn,base

Author

Parthasarathy Nambi, Jun 09 2005

Status

approved