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Expansion of (theta_3(x) - 1)^4 / (8 * (3 - theta_3(x))).
4

%I #10 Sep 14 2021 20:48:51

%S 1,1,1,5,6,7,14,19,29,41,56,88,123,170,245,351,500,704,1003,1427,2021,

%T 2867,4060,5763,8176,11585,16430,23301,33032,46826,66393,94131,133458,

%U 189209,268243,380315,539190,764422,1083758,1536495,2178361,3088357,4378496,6207581

%N Expansion of (theta_3(x) - 1)^4 / (8 * (3 - theta_3(x))).

%C Number of compositions (ordered partitions) of n into 4 or more squares.

%H <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>

%F a(n) = Sum_{k=4..n} A337165(n,k). - _Alois P. Heinz_, Sep 14 2021

%p b:= proc(n, t) option remember; `if`(n=0, `if`(t=0, 1, 0), add((

%p s->`if`(s>n, 0, b(n-s, max(0, t-1))))(j^2), j=1..isqrt(n)))

%p end:

%p a:= n-> b(n, 4):

%p seq(a(n), n=4..47); # _Alois P. Heinz_, Sep 14 2021

%t nmax = 47; CoefficientList[Series[(EllipticTheta[3, 0, x] - 1)^4/(8 (3 - EllipticTheta[3, 0, x])), {x, 0, nmax}], x] // Drop[#, 4] &

%Y Cf. A000290, A006456, A337165, A347805, A347806, A347808, A347809.

%K nonn

%O 4,4

%A _Ilya Gutkovskiy_, Sep 14 2021