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 A111921 #10 Feb 16 2025 08:32:58
%S A111921 1,16,432,6912,864000,864000,296352000,4741632000,128024064000,
%T A111921 128024064000,170400029184000,170400029184000,374368864117248000,
%U A111921 374368864117248000,14974754564689920,239596073035038720
%N A111921 Denominator of x(n) = Sum_{k=1..n} ((odd part of k)/(k^4)).
%C A111921 Numerator of x(n) = A111920(n);
%C A111921 x(n) = A111920(n)/a(n) -> 14*zeta(3)/15.
%D A111921 G. Pólya and G. Szegő, Problems and Theorems in Analysis II (Springer 1924, reprinted 1972), Part Eight, Chap. 1, Sect. 6, Problem 50.
%H A111921 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/OddPart.html">Odd Part</a>
%H A111921 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/AperysConstant.html">Apery's constant</a>
%H A111921 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RiemannZetaFunction.html">Riemann Zeta Function</a>
%Y A111921 Cf. A000265, A002117, A111930, A111919, A111920, A111923.
%K A111921 nonn,frac
%O A111921 1,2
%A A111921 _Reinhard Zumkeller_, Aug 21 2005