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A174180 Numbers n>0 such that 10^n+2^n+1 is prime. 0
1, 3, 9, 17, 19, 27, 351, 813, 869, 1387 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

LINKS

Table of n, a(n) for n=1..10.

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

Sequence in context: A056403 A181349 A240094 * A106676 A050795 A050797

Adjacent sequences:  A174177 A174178 A174179 * A174181 A174182 A174183

KEYWORD

nonn,more

AUTHOR

Vincenzo Librandi, Mar 11 2010

EXTENSIONS

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

STATUS

approved

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Last modified June 18 14:52 EDT 2019. Contains 324213 sequences. (Running on oeis4.)