OFFSET
0,8
COMMENTS
Number of compositions (ordered partitions) of n into partial sums of primes (A007504).
Conjecture: every number > 3 is the sum of at most 5 partial sums of primes.
LINKS
Eric Weisstein's World of Mathematics, Prime Sums
FORMULA
G.f.: 1/(1 - Sum_{j>=1} x^(Sum_{i=1..j} prime(i))).
EXAMPLE
a(11) = 4 because we have [5, 2, 2, 2], [2, 5, 2, 2], [2, 2, 5, 2] and [2, 2, 2, 5].
MATHEMATICA
nmax = 60; CoefficientList[Series[1/(1 - Sum[x^Sum[Prime[i], {i, 1, j}], {j, 1, nmax}]), {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 24 2017
STATUS
approved