A174180 - OEIS

A174180

Numbers k > 0 such that 10^k + 2^k + 1 is prime.

1, 3, 9, 17, 19, 27, 351, 813, 869, 1387, 34383

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OFFSET

1,2

COMMENTS

Terms greater than 351 yield probable primes. Next term > 10000. - Vaclav Kotesovec, Apr 30 2014

LINKS

MATHEMATICA

Select[Range[1, 1000], PrimeQ[10^#+2^#+1]&] (* Vaclav Kotesovec, Apr 30 2014 *)

PROG

(Magma) [n: n in [1..800] | IsPrime(10^n+2^n+1) ];

CROSSREFS

KEYWORD

nonn,more,changed

AUTHOR

EXTENSIONS

a(8)-a(10) from Vaclav Kotesovec, Apr 30 2014

a(11) from Michael S. Branicky, Oct 10 2024

STATUS

approved