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 A202448 Least k such that k*n!! +1 is a prime number. 0
 1, 1, 2, 2, 2, 2, 2, 2, 8, 2, 10, 3, 2, 6, 10, 3, 2, 2, 14, 5, 10, 9, 6, 2, 22, 10, 4, 2, 26, 2, 22, 3, 8, 11, 30, 11, 6, 4, 2, 15, 52, 10, 22, 13, 10, 9, 34, 11, 18, 18, 2, 10, 26, 12, 4, 34, 4, 18, 26, 16, 34, 25, 22, 12, 14, 32, 50, 24, 4, 8, 12, 14, 26, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE a(9) = 8 because 8*9!! + 1 = 8*945 + 1 = 7561 is prime. MATHEMATICA Table[k = 0; While[!PrimeQ[k*n!! +1], k++]; k, {n, 85}] CROSSREFS Cf. A006882. Sequence in context: A140818 A139813 A172009 * A129381 A139514 A190617 Adjacent sequences:  A202445 A202446 A202447 * A202449 A202450 A202451 KEYWORD nonn AUTHOR Michel Lagneau, Dec 19 2011 STATUS approved

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