OFFSET
2,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 2..10000
FORMULA
G.f.: ( x + Sum_{k>=1} x^prime(k) )^2.
MAPLE
b:= proc(n) option remember; series(`if`(n=0, 1, x*add(
`if`(j=1 or isprime(j), b(n-j), 0), j=1..n)), x, 3)
end:
a:= n-> coeff(b(n), x, 2):
seq(a(n), n=2..88); # Alois P. Heinz, Feb 24 2021
MATHEMATICA
nmax = 88; CoefficientList[Series[(x + Sum[x^Prime[k], {k, 1, nmax}])^2, {x, 0, nmax}], x] // Drop[#, 2] &
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 24 2021
STATUS
approved