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A193177 Numbers n such that 2*17^n - 1 is prime. 1
2, 30, 74, 122, 386, 476, 630 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Is it true that a(n)= 0 or 2 (mod 6) and a(n)= 0 or 2 (mod 4)?

Yes. This can be proved mod 21. [Charles R Greathouse IV, Jul 31 2011]

LINKS

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

MATHEMATICA

Table[If[PrimeQ[2*17^m-1], m], {m, 1, 2000}]//Union

PROG

(PARI) forstep(n=2, 1e4, [4, 2], if(ispseudoprime(2*17^n-1), print1(n", "))) \\ Charles R Greathouse IV, Jul 31 2011

CROSSREFS

Sequence in context: A244379 A189100 A085637 * A157870 A285991 A078838

Adjacent sequences: A193174 A193175 A193176 * A193178 A193179 A193180

KEYWORD

nonn

AUTHOR

José María Grau Ribas, Jul 17 2011

STATUS

approved

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Last modified March 28 23:19 EDT 2023. Contains 361596 sequences. (Running on oeis4.)