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%I #22 Feb 19 2013 04:30:34
%S 1,1,3,3,8,1,1,1,5,7,19,7,5,15,7,17,5,3,9,11,63,9,5,1,53,27,51,11,3,
%T 11,13,15,17,35,1,17,21,13,139,61,3,13,1,7,147,23,123,47,41,35,11,39,
%U 69,21,123,29,27,49,3,9,37,171,57,1,31,37,5,61,27,31,53
%N Minimal m >= 1 such that floor((2*n - 1)!!/m) - 2 is prime.
%e (2*6-1)!! = 11!! = 11 * 9 * 7 * 5 * 3 * 1 = 10395. Floor(10395/1) - 2 = 10395 - 2 = 10393 = 19 * 547 is not prime, and floor(10395/2) - 2 = 5197 - 2 = 5195 = 5 * 1039 is not prime, but floor(10395/3) - 2 = 3465 - 2 = 3463 is prime, so a(6) = 3.
%p a:= proc(n) local m;
%p for m while not isprime(iquo(doublefactorial(2*n-1), m)-2)
%p do od; m
%p end:
%p seq(a(n), n=3..70); # _Alois P. Heinz_, Feb 18 2013
%Y Cf. A212281, A212282, A212321.
%K nonn
%O 3,3
%A _Vladimir Shevelev_, Feb 14 2013
%E More terms from _Alois P. Heinz_, Feb 18 2013
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