OFFSET
0,3
COMMENTS
Number of compositions of n into parts where there are A000120(k) sorts of part k.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..2984
FORMULA
G.f.: 1 / (1 - Sum_{k>=1} A000120(k) * x^k).
MAPLE
h:= proc(n) option remember; add(j, j=Bits[Split](n)) end:
a:= proc(n) option remember; `if`(n=0, 1,
add(a(n-i)*h(i), i=1..n))
end:
seq(a(n), n=0..36);
MATHEMATICA
h[n_] := h[n] = DigitCount[n, 2, 1];
a[n_] := a[n] = If[n == 0, 1,
Sum[a[n - i]*h[i], {i, 1, n}]];
Table[a[n], {n, 0, 36}] (* Jean-François Alcover, Apr 14 2022, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 02 2021
STATUS
approved