A294396 Numbers k such that 12*10^k + 1 is prime.

0, 2, 38, 80, 9230, 25598, 39500

Offset

1,2

Comments

k must be even since 12*10^k + 1 is divisible by 11 if k is odd. - Robert G. Wilson v, Feb 12 2018

a(7) > 27440. - Robert G. Wilson v, Feb 17 2018

a(8) > 10^5. - Jeppe Stig Nielsen, Jan 31 2023

Links

Table of n, a(n) for n=1..7.

Example

13 and 1201 are prime, so 0 and 2 are the initial values.

Mathematica

ParallelMap[ If[ PrimeQ[12*10^# +1], #, Nothing] &, 2 + 6Range@ 4500] (* Robert G. Wilson v, Feb 13 2018 *)

Prog

(PARI) isok(k) = isprime(12*10^k + 1); \\ Altug Alkan, Mar 04 2018

Crossrefs

Cf. A001562, A096507, A056797, A056807, A056806, A102940, A056805, A056804, A096508, A102975, A289051, A099017, A295325, A273002, A102945, A282456, A267420.

Cf. A062339 (primes with digit sum 4).

Sequence in context: A050899 A068401 A173026 * A075459 A050248 A337773

Adjacent sequences: A294393 A294394 A294395 * A294397 A294398 A294399

Keyword

nonn,more

Author

Patrick A. Thomas, Feb 12 2018

Extensions

a(5) from Robert G. Wilson v, Feb 12 2018

a(6) from Robert G. Wilson v, Feb 13 2018

a(7) from Jeppe Stig Nielsen, Jan 28 2023

Status

approved