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 A212321 Minimal m >= 1 such that floor((2*n-1)!!/m) + 2 is prime. 5
 1, 1, 1, 1, 1, 3, 9, 5, 5, 3, 1, 1, 7, 1, 13, 11, 15, 21, 23, 15, 17, 5, 25, 25, 7, 85, 9, 25, 1, 21, 9, 13, 17, 5, 49, 39, 45, 1, 43, 51, 145, 17, 143, 85, 19, 81, 63, 43, 47, 77, 23, 1, 3, 21, 17, 47, 37, 3, 7, 67, 23, 23, 25, 45, 81, 5, 39, 145, 71, 21, 41 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 LINKS MAPLE a:= proc(n) local m;       for m while not isprime(iquo(doublefactorial(2*n-1), m)+2)       do od; m     end: seq(a(n), n=1..50);  # Alois P. Heinz, Feb 18 2013 CROSSREFS Cf. A212281, A212282. Sequence in context: A070341 A245719 A085851 * A306552 A092041 A317904 Adjacent sequences:  A212318 A212319 A212320 * A212322 A212323 A212324 KEYWORD nonn AUTHOR Vladimir Shevelev, Feb 14 2013 EXTENSIONS More terms from Alois P. Heinz, Feb 18 2013 STATUS approved

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Last modified July 23 20:32 EDT 2019. Contains 325264 sequences. (Running on oeis4.)