A171612 Integers n such that (25*10^n)+1 is prime.

1, 8, 255, 320, 609, 688, 1436, 3271, 3921, 6520, 19604

Offset

1,2

Comments

No others less than 20000.

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "25001".

Links

Table of n, a(n) for n=1..11.

Makoto Kamada, List of near-repdigit-related prime numbers.

Index entries for primes involving repunits.

Example

For n=8 we have (25*10^8)+1 = 25*100000000+1 = 2500000000+1 = 2500000001, which is prime.

Crossrefs

Cf. A056797, A056804, A056805, A056806, A056807

Sequence in context: A213412 A226428 A277421 * A053717 A267250 A034674

Adjacent sequences: A171609 A171610 A171611 * A171613 A171614 A171615

Keyword

more,nonn

Author

Julien Peter Benney (jpbenney(AT)ftml.net), Dec 13 2009

Extensions

Edited by Ray Chandler, Dec 23 2010

Status

approved