This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A280618 #20 Feb 16 2025 08:33:39
%S A280618 0,0,1,0,0,0,0,0,0,2,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,
%T A280618 0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,2,0,0,
%U A280618 0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
%N A280618 Expansion of (Sum_{k>=1} x^(k^3))^2.
%C A280618 Number of ways to write n as an ordered sum of two positive cubes.
%H A280618 Antti Karttunen, <a href="/A280618/b280618.txt">Table of n, a(n) for n = 0..65537</a>
%H A280618 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CubicNumber.html">Cubic Number</a>
%H A280618 <a href="/index/Su#ssq">Index entries for sequences related to sums of cubes</a>
%F A280618 G.f.: (Sum_{k>=1} x^(k^3))^2.
%e A280618 a(9) = 2 because we have [8, 1] and [1, 8].
%t A280618 nmax = 150; CoefficientList[Series[(Sum[x^(k^3), {k, 1, nmax}])^2, {x, 0, nmax}], x]
%o A280618 (PARI)
%o A280618 A010057(n) = ispower(n, 3);
%o A280618 A280618(n) = if(n<2, 0, sum(r=1,sqrtnint(n-1,3),A010057(n-(r^3)))); \\ _Antti Karttunen_, Nov 30 2021
%Y A280618 Cf. A000578, A001235 (positions of terms > 3), A003325 (of nonzero terms), A010057, A063725, A173677.
%K A280618 nonn
%O A280618 0,10
%A A280618 _Ilya Gutkovskiy_, Jan 06 2017