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 A224903 #17 Mar 17 2024 03:18:37
%S A224903 2,32,242,512,1562,3872,5602,8192,19682,24992,32210,61952,61882,89632,
%T A224903 189002,131072,177482,314912,275122,399872,677842,515360,585122,
%U A224903 991232,976562,990112,1594322,1434112,1465082,3024032,1908610,2097152,3897410,2839712,4375162,5038592,3852442
%N A224903 a(n) = sigma(2*n^4) - sigma(n^4).
%C A224903 Here sigma(n) = A000203(n), the sum of the divisors of n.
%F A224903 a(n) = A054785(n^4).
%F A224903 Logarithmic derivative of A224902.
%F A224903 Sum_{k=1..n} a(k) ~ c * n^5, where c = (31/115) * zeta(5) * Product_{p prime} (1 + 1/p^2 + 1/p^3 + 1/p^5) = 0.51764417195990550114... . - _Amiram Eldar_, Mar 17 2024
%e A224903 L.g.f.: L(x) = 2*x + 32*x^2/2 + 242*x^3/3 + 512*x^4/4 + 1562*x^5/5 +...
%e A224903 where exponentiation yields the g.f. of A224902:
%e A224903 exp(L(x)) = 1 + 2*x + 18*x^2 + 114*x^3 + 450*x^4 + 2298*x^5 +...
%t A224903 a[n_] := DivisorSigma[1, 2*n^4] - DivisorSigma[1, n^4]; Array[a, 50] (* _Amiram Eldar_, Mar 17 2024 *)
%o A224903 (PARI) {a(n)=sigma(2*n^4)-sigma(n^4)}
%o A224903 for(n=1, 30, print1(a(n), ", "))
%Y A224903 Cf. A224902, A054785, A000203, A013663.
%K A224903 nonn
%O A224903 1,1
%A A224903 _Paul D. Hanna_, Jul 24 2013