A278929 Expansion of 1/(1 - Sum_{k>=1} x^(prime(k)^3)).
1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 2, 0, 0, 0, 0, 1, 0, 0, 3, 0, 0, 0, 0, 1, 0, 0, 4, 0, 0, 1, 0, 1, 0, 0, 5, 0, 0, 3, 0, 1, 0, 0, 6, 0, 0, 6, 0, 1, 0, 0, 7, 0, 0, 10, 0, 1, 1, 0, 8, 0, 0, 15, 0, 1, 4, 0, 9, 0, 0, 21
Offset: 0
Keywords
Examples
a(35) = 2 because we have [8, 27] and [27, 8].
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Programs
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Maple
N:= 200: Primes:= select(isprime, [2,seq(i,i=3..floor(N^(1/3)),2)]): G:= 1/(1- add(x^(Primes[i]^3),i=1..nops(Primes))): S:= series(G,x,N+1): seq(coeff(S,x,j),j=0..N); # Robert Israel, Jan 23 2019
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Mathematica
nmax = 120; CoefficientList[Series[1/(1 - Sum[x^Prime[k]^3, {k, 1, nmax}]), {x, 0, nmax}], x]
Formula
G.f.: 1/(1 - Sum_{k>=1} x^(prime(k)^3)).
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