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 A035092 Smallest k such that (n^2)*k + 1 is prime. 10
 1, 1, 2, 1, 4, 1, 4, 3, 2, 1, 6, 3, 4, 1, 8, 1, 12, 4, 30, 1, 2, 3, 24, 1, 18, 1, 2, 4, 12, 2, 16, 12, 2, 3, 6, 1, 4, 13, 6, 1, 10, 2, 12, 6, 2, 6, 4, 8, 6, 9, 6, 9, 28, 1, 4, 1, 10, 3, 6, 4, 46, 4, 4, 3, 4, 1, 4, 3, 22, 6, 10, 2, 4, 1, 2, 7, 22, 3, 6, 4, 6, 3, 10, 1, 4, 3, 2, 4, 6, 1, 10, 4, 2, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Michael De Vlieger, Table of n, a(n) for n = 1..10000 EXAMPLE a(40) = 1 because in 1600k + 1 at k = 1, 1601 is the smallest prime; a(61) = 46 because in the 46*46*k + 1 sequence the first prime appears at k = 46; it is 171167. MATHEMATICA Table[k = 1; While[! PrimeQ[k (n^2) + 1], k++]; k, {n, 94}] (* Michael De Vlieger, Dec 17 2016 *) PROG (PARI) a(n)=k=1; while(!isprime(k*n^2+1), k++); k vector(100, n, a(n)) \\ Derek Orr, Oct 01 2014 CROSSREFS Analogous case is A034693. See also A005574 and A002496. Sequence in context: A322968 A072721 A285711 * A160598 A107457 A112350 Adjacent sequences:  A035089 A035090 A035091 * A035093 A035094 A035095 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified September 16 18:56 EDT 2019. Contains 327117 sequences. (Running on oeis4.)