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 A231374 Numbers n such that 3^9*2^n - 1 is prime. 0
 4, 7, 19, 22, 32, 46, 50, 62, 83, 103, 124, 142, 190, 230, 256, 260, 422, 596, 1084, 2270, 2770, 5366, 5434, 5762, 6826, 9239, 15211, 22556, 58790, 81319, 172510, 225350, 236326, 258592, 445364, 975020 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Riesel Primes with k = 3^9 = 19683. Checked up to n = 1000000. LINKS Table of n, a(n) for n=1..36. EXAMPLE 19683*2^4-1=314927 is a prime number. MATHEMATICA i=0; Table[While[i++; cp=19683*2^i-1; !PrimeQ[cp]]; i, {j, 1, 20}] PROG (PARI) is(n)=ispseudoprime(3^9*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017 CROSSREFS Cf. A002235, A002236, A050539, A050566, A050880, A230527, A230537, A212311. Sequence in context: A132207 A097537 A032723 * A173017 A063605 A024824 Adjacent sequences: A231371 A231372 A231373 * A231375 A231376 A231377 KEYWORD nonn,hard AUTHOR Lei Zhou, Nov 08 2013 STATUS approved

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Last modified September 8 21:41 EDT 2024. Contains 375759 sequences. (Running on oeis4.)