A007919 Smallest k such that k*n is a double factorial.

1, 1, 1, 2, 3, 8, 15, 1, 105, 384, 945, 4, 10395, 46080, 1, 3, 2027025, 2560, 34459425, 192, 5, 3715891200, 13749310575, 2, 81081, 1961990553600, 35, 23040, 213458046676875, 128, 6190283353629375, 12

Offset

1,4

Links

Robert G. Wilson v, Table of n, a(n) for n = 1..817

F. Smarandache, Only Problems, Not Solutions!.

Index entries for sequences related to factorial numbers

Mathematica

f[n_] := Block[{k = 1}, While[Mod[k!!, n] > 0, k++];   k!!/n]; Array[f, 35] (* Robert G. Wilson v, Feb 18 2018 *)

Crossrefs

Cf. A006882.

Sequence in context: A005316 A076876 A124495 * A249167 A205101 A069752

Adjacent sequences: A007916 A007917 A007918 * A007920 A007921 A007922

Keyword

nonn

Author

R. Muller

Extensions

a(10) corrected by Sean A. Irvine, Feb 18 2018

Status

approved