A083092 Numbers n such that 7*5^n + 2 is a prime.

1, 3, 29, 203, 297, 617, 1211, 2969, 3037, 6489, 28029, 32229, 63927

Offset

1,2

Comments

Values corresponding to 29, 203, 297, 617 and 1211 (848 digits) have been certified prime with Primo. Values for 2969 (2077 digits) and 3037 (2124 digits) are probable primes. There are no other terms <= 4000.

a(14) > 10^5. - Tyler NeSmith

Links

Table of n, a(n) for n=1..13.

Example

37, 877, 1303851604461669921877 are 7*5^1 + 2, 7*5^3 + 2 and 7*5^29 + 2.
7*5^203 + 2 has 143 digits.

Prog

(PARI) for(n=1, 4000, if(isprime(7*5^n+2), print1(n, ", ")))

Crossrefs

Sequence in context: A227694 A118584 A126185 * A174419 A220548 A153825

Adjacent sequences: A083089 A083090 A083091 * A083093 A083094 A083095

Keyword

nonn

Author

Rick L. Shepherd, Apr 23 2003

Extensions

a(10)-a(13) from Tyler NeSmith, Dec 14 2020

Status

approved