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 A057325 First member of a prime quadruple in a p^2+p-1 progression. 3
 3, 11, 53, 1693, 2663, 4423, 16831, 17609, 36229, 49801, 94961, 121493, 150869, 176303, 183761, 188011, 210901, 213833, 218579, 272903, 300301, 329671, 439511, 444791, 453023, 469613, 518813, 531911, 546071, 559703, 570719, 614279, 705781 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS I found only one prime quintuplet so far: (3,11,131,17291,298995971). Subsequence of A057324. - Pierre CAMI, Sep 13 2013 LINKS Pierre CAMI, Table of n, a(n) for n = 0..6777 EXAMPLE 3 -> 3^2+3-1 = 11 -> 11^2+11-1 = 131 -> 131^2+131-1 = 17291 hence the quadruple (3,11,131,17291). MATHEMATICA okQ[n_] := And@@PrimeQ/@NestList[#^2 + # - 1 &, n, 3]; Select[ Prime[ Range[ 60000]], okQ] (* Harvey P. Dale, Jan 05 2011 *) PROG (PARI) is(n)=for(k=1, 4, if(!isprime(n), return(0)); n=n^2+n-1); 1 \\ Charles R Greathouse IV, Sep 13 2013 CROSSREFS Cf. A053184, A053185, A057324. Sequence in context: A156171 A129093 A259106 * A302760 A054700 A009280 Adjacent sequences:  A057322 A057323 A057324 * A057326 A057327 A057328 KEYWORD nonn AUTHOR Patrick De Geest, Aug 15 2000 STATUS approved

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Last modified April 5 00:43 EDT 2020. Contains 333238 sequences. (Running on oeis4.)