OFFSET
0,6
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 0..10000 (first 1000 terms from T. D. Noe)
FORMULA
G.f.: Product_{p prime} Product_{k >= 1} (1 + x^(p^k)).
MATHEMATICA
CoefficientList[Series[Product[Product[1 +x^(Prime[n]^k), {k, 1, 9}], {n, 1, 25}], {x, 0, 100}], x] (* G. C. Greubel, May 09 2019 *)
PROG
(Haskell)
import Data.MemoCombinators (memo2, integral)
a054685 n = a054685_list !! n
a054685_list = map (p' 2) [0..] where
p' = memo2 integral integral p
p _ 0 = 1
p k m = if m < pp then 0 else p' (k + 1) (m - pp) + p' (k + 1) m
where pp = a000961 k
-- Reinhard Zumkeller, Nov 23 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
David W. Wilson, Apr 19 2000
STATUS
approved