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A279372
Expansion of (Sum_{k>=1} x^(prime(k)^2))^2.
0
0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
OFFSET
0,14
COMMENTS
Number of ordered ways of writing n as the sum of two squares of primes (A001248).
FORMULA
G.f.: (Sum_{k>=1} x^(prime(k)^2))^2.
a(n) = Sum_{i=1..n} A302048(i)*A302048(n-i). - Ridouane Oudra, Nov 21 2020
EXAMPLE
a(13) = 2 because we have [4, 9] and [9, 4].
MATHEMATICA
nmax = 125; CoefficientList[Series[(Sum[x^Prime[k]^2, {k, 1, nmax}])^2, {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Dec 24 2016
STATUS
approved