OFFSET
4,2
MAPLE
q:= proc(n) option remember; nops(ifactors(n)[2])<2 end:
b:= proc(n, t) option remember;
`if`(n=0, `if`(t=0, 1, 0), `if`(t<1, 0, add(
`if`(q(j), b(n-j, t-1), 0), j=1..n)))
end:
a:= n-> b(n, 4):
seq(a(n), n=4..54); # Alois P. Heinz, Feb 05 2021
MATHEMATICA
nmax = 54; CoefficientList[Series[Sum[Boole[PrimePowerQ[k] || k == 1] x^k, {k, 1, nmax}]^4, {x, 0, nmax}], x] // Drop[#, 4] &
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 05 2021
STATUS
approved