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A316331
a(n) = A000085(4*n+1)/2^n.
4
1, 13, 655, 71063, 13237457, 3748521653, 1495006933759, 796798642614895, 546144645571635169, 467512355698028529821, 488384275088035513080239, 611057820865315450415912327, 901643505614430586911510015025, 1548711768835068239482321088560837
OFFSET
0,2
LINKS
S. Chowla, I. N. Herstein and W. K. Moore, On recursions connected with symmetric groups I, Canad. J. Math. 3 (1951) 328-334.
Dongsu Kim and Jang Soo Kim, A combinatorial approach to the power of 2 in the number of involutions, J. Comb. Theory Ser. A 117 (8) (2010): 1082-1094.
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 09 2018, following a suggestion from Doron Zeilberger
STATUS
approved