OFFSET
0,2
MAPLE
wt := proc(n) local w, m, i; w := 0; m := n; while m > 0 do i := m mod 2; w := w+i; m := (m-i)/2; od; w; end:
f:=proc(n) local t1, k; global wt; t1:=0; for k from 0 to 20 do if k mod 2 = 0 then t1:=t1+binomial(wt(n+k), k); fi; od; t1; end;
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 01 2009
STATUS
approved