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Number of partitions of 2n prime to 3,5 with all odd parts occurring with even multiplicities. There is no restriction on the even parts.
2

%I #23 Sep 01 2015 19:43:29

%S 1,2,4,6,10,14,20,28,40,54,72,96,126,164,212,274,350,444,560,704,878,

%T 1092,1352,1668,2048,2506,3056,3714,4500,5436,6552,7872,9436,11280,

%U 13456,16012,19014,22532,26648,31452,37052,43572,51148,59940,70128,81922,95548

%N Number of partitions of 2n prime to 3,5 with all odd parts occurring with even multiplicities. There is no restriction on the even parts.

%C This is also the sequence A103257/(theta_4(0,x^(15))).

%H Alois P. Heinz, <a href="/A103259/b103259.txt">Table of n, a(n) for n = 0..10000</a>

%H Noureddine Chair, <a href="http://arxiv.org/abs/hep-th/0409011">Partition Identities From Partial Supersymmetry</a>, arXiv:hep-th/0409011v1, 2004.

%F G.f.: (theta_4(0, x^3)*theta_4(0, x^5))/(theta_4(0, x)*theta_4(0, x^(15))).

%F G.f.: (E(2)*E(3)^2*E(5)^2*E(30)) / (E(1)^2*E(6)*E(10)*E(15)^2) where E(k) = prod(n>=1, 1-q^k ). - _Joerg Arndt_, Sep 01 2015

%F a(n) ~ exp(2*Pi*sqrt(2*n/15)) / (2^(3/4) * 15^(1/4) * n^(3/4)). - _Vaclav Kotesovec_, Sep 01 2015

%e a(5) = 14 because 10 can be written as 8+2 = 8+1+1 = 4+4+2 = 4+4+1+1 = 4+2+2+2 = 4+2+2+1+1 = 4+2+1+1+1+1 = 4+1+1+1+1+1+1 = 2+2+2+2+2 = 2+2+2+2+1+1 = 2+2+2+1+1+1+1 = 2+2+1+1+1+1+1+1 = 2+1+1+1+1+1+1+1+1 = 1+1+1+1+1+1+1+1+1+1.

%p series(product((1+x^k)*(1-x^(3*k))*(1-x^(5*k))*(1+x^(15*k))/((1-x^k)*(1+x^(3*k))*(1+x^(5*k))*(1-x^(15*k))),k=1..100),x=0,100);

%t nmax = 50; CoefficientList[Series[Product[(1+x^k)*(1-x^(3*k))*(1-x^(5*k))*(1+x^(15*k))/((1-x^k)*(1+x^(3*k))*(1+x^(5*k))*(1-x^(15*k))), {k, 1, nmax}], {x, 0, nmax}], x] (* _Vaclav Kotesovec_, Sep 01 2015 *)

%o (PARI) q='q+O('q^33); E(k)=eta(q^k);

%o Vec( (E(2)*E(3)^2*E(5)^2*E(30)) / (E(1)^2*E(6)*E(10)*E(15)^2) ) \\ _Joerg Arndt_, Sep 01 2015

%Y Cf. A102346, A103257.

%K nonn

%O 0,2

%A _Noureddine Chair_, Feb 15 2005

%E Example corrected by _Vaclav Kotesovec_, Sep 01 2015

%E Maple program corrected by _Vaclav Kotesovec_, Sep 01 2015

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Last modified September 24 10:05 EDT 2024. Contains 376196 sequences. (Running on oeis4.)