OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..2000
FORMULA
Coefficient of x^n in expansion of 1/(1-Sum_{d divides n} x^d ).
MAPLE
with(numtheory): G:=proc(n) local DV: DV:=divisors(n): 1/(1-sum(x^DV[j], j=1..tau(n))) end: seq(coeff(series(G(n), x, 80), x, n), n=0..44); # Emeric Deutsch, Feb 16 2005
# second Maple program:
a:= proc(n) option remember; local b, l;
l, b:= numtheory[divisors](n),
proc(m) option remember; `if`(m=0, 1,
add(`if`(j>m, 0, b(m-j)), j=l))
end; b(n)
end:
seq(a(n), n=0..50); # Alois P. Heinz, Mar 28 2017
MATHEMATICA
a[n_] := SeriesCoefficient[1/(1-DivisorSum[n, x^#&]), {x, 0, n}]; Array[a, 50] (* Jean-François Alcover, Apr 06 2017 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Dec 29 2004
EXTENSIONS
More terms from Emeric Deutsch, Feb 16 2005
a(0)=1 prepended by Alois P. Heinz, Nov 08 2023
STATUS
approved