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A212321
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Minimal m >= 1 such that floor((2*n-1)!!/m) + 2 is prime.
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6
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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
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OFFSET
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1,6
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LINKS
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MAPLE
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a:= proc(n) local m;
for m while not isprime(iquo(doublefactorial(2*n-1), m)+2)
do od; m
end:
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MATHEMATICA
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a[n_] := Module[{m}, For[m = 1, True, m++, If[PrimeQ[Floor[(2n-1)!!/m]+2], Return[m]]]];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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