A273994 Number of endofunctions on [n] whose cycle lengths are Fibonacci numbers.

1, 1, 4, 27, 250, 2975, 43296, 744913, 14797036, 333393345, 8403026320, 234300271811, 7161316358616, 238108166195263, 8556626831402560, 330494399041444425, 13654219915946513296, 600870384794864432897, 28060233470995898505024, 1386000542545570348128235

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..386

Maple

b:= proc(n) option remember; local r, f, g;
      if n=0 then 1 else r, f, g:= $0..2;
      while f<=n do r:= r+(f-1)!*b(n-f)*
         binomial(n-1, f-1); f, g:= g, f+g
      od; r fi
    end:
a:= n-> add(b(j)*n^(n-j)*binomial(n-1, j-1), j=0..n):
seq(a(n), n=0..20);

Mathematica

b[n_] := b[n] = Module[{r, f, g}, If[n == 0, 1, {r, f, g} = {0, 1, 2}; While[f <= n, r = r + (f - 1)!*b[n - f]*Binomial[n - 1, f - 1]; {f, g} = {g, f + g}]; r]];
a[0] = 1; a[n_] := Sum[b[j]*n^(n - j)*Binomial[n - 1, j - 1], {j, 0, n}];
Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Jun 06 2018, from Maple *)

Crossrefs

Cf. A000045, A060435, A116956, A273001, A273996, A273997, A273998, A305824.

Sequence in context: A239370 A239369 A246526 * A239378 A239376 A239373

Adjacent sequences: A273991 A273992 A273993 * A273995 A273996 A273997

Keyword

nonn

Author

Alois P. Heinz, Jun 06 2016

Status

approved