OFFSET
1,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..200 (first 100 terms from Max Alekseyev)
FORMULA
a(n) = Sum_{k=1..n} k*A008304(n,k). - Max Alekseyev, May 22 2012
MAPLE
b:= proc(u, o, t, k) option remember; `if`(t=k, (u+o)!,
`if`(max(t, u)+o<k, 0, add(b(u+j-1, o-j, t+1, k), j=1..o)+
add(b(u-j, o+j-1, 1, k), j=1..u)))
end:
a:= n-> add(b(0, n, 0, k), k=1..n) -n*b(0, n, 0, n+1):
seq(a(n), n=1..25); # Alois P. Heinz, Oct 16 2013
MATHEMATICA
nn=30; f[list_]:=Total[Table[list[[i]]*i, {i, 1, Length[list]}]]; a[r_]:=Apply[Plus, Table[Normal[Series[y x^(r+1)/(1-Sum[y x^i, {i, 1, r}]), {x, 0, nn}]][[n]]/(n+r)!, {n, 1, nn-r}]]/.y->-1; Map[f, Map[Select[#, #>0&]&, Transpose[Prepend[Table[Drop[Range[0, nn]! CoefficientList[Series[1/(1-x-a[n+1])-1/(1-x-a[n]), {x, 0, nn}], x], 1], {n, 1, 28}], Table[1, {nn}]]]]] (* Geoffrey Critzer, Feb 25 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
David W. Wilson, Sep 07 2001
STATUS
approved