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 A261428 Number of permutations p of [2n] without fixed points such that p^8 = Id. 3
 1, 1, 9, 105, 7665, 303345, 25893945, 1765268505, 345763843425, 42813526781025, 9399638261838825, 1573582072888650825, 563295733721953657425, 139523356060051359020625, 55722660999371761475705625, 17053184982967015188566885625, 9496879931794641573011009810625 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..250 FORMULA a(n) = (2n)! * [x^(2n)] exp(x^2/2+x^4/4+x^8/8). MAPLE b:= proc(n) option remember; `if`(n<0, 0, `if`(n=0, 1,        add(mul(n-i, i=1..j-1)*b(n-j), j=[2, 4, 8])))     end: a:= n-> b(2*n): seq(a(n), n=0..20); CROSSREFS Bisection of column k=8 of A261430. Cf. A053498. Sequence in context: A110698 A012485 A052503 * A122569 A309652 A316145 Adjacent sequences:  A261425 A261426 A261427 * A261429 A261430 A261431 KEYWORD nonn AUTHOR Alois P. Heinz, Aug 18 2015 STATUS approved

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Last modified February 29 01:30 EST 2020. Contains 332353 sequences. (Running on oeis4.)