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 A180431 Numbers n such that 4*17^n+1 is prime. 1
 0, 6, 522, 178438 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For n>0, members of the sequence may only be of form 4k+2 (otherwise the expression is divisible by 3 or 5). Therefore members of the sequence are a subset of A005574 and are Generalized Fermat primes. LINKS Table of n, a(n) for n=1..4. Eric Weisstein's World of Mathematics, Generalized Fermat Number. EXAMPLE For a(2) = 6 we have 4*17^6+1 = 96550277, which is prime. MATHEMATICA Do[ If[ PrimeQ[ 4*17^n+1], Print[ n ]], {n, 0, 10000}] PROG (PARI) is(n)=isprime(4*17^n+1) \\ Charles R Greathouse IV, May 15 2013 CROSSREFS Cf. A005574. Sequence in context: A003395 A222607 A000411 * A202967 A230330 A252174 Adjacent sequences: A180428 A180429 A180430 * A180432 A180433 A180434 KEYWORD nonn,more AUTHOR Serge Batalov, Sep 04 2010 STATUS approved

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Last modified May 28 12:54 EDT 2024. Contains 372913 sequences. (Running on oeis4.)