OFFSET
0,5
LINKS
Michael De Vlieger, Table of n, a(n) for n = 0..450
Paulo H. L. Martins, Ronald Dickman, and Robert M. Ziff, Percolation in two-species antagonistic random sequential adsorption in two dimensions, arXiv:2211.04622 [cond-mat.stat-mech], 2022.
FORMULA
a(n+1) = n*(a(n) + a(n-1) + n - 2), a(0)=1, a(1)=0.
a(n) = (A000166(n) - n + 1)/2.
E.g.f.: cosh(log(1/(1-x)) - x). - Geoffrey Critzer, Jun 23 2014
MAPLE
a := proc (n) local x, y, t, k; if n = 0 then 1 elif n = 1 then 0 else x := 1; y := 0; for k from 2 to n do t := y; y := (k-1)*(x+y+k-3); x := t end do; y end if end proc;
MATHEMATICA
nn=23; Range[0, nn]!*CoefficientList[Series[Cosh[Log[1/(1-x)]-x], {x, 0, nn}], x] (* Geoffrey Critzer, Jun 23 2014 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
José H. Nieto S., Sep 16 2012
STATUS
approved