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 A164109 #24 Aug 19 2025 04:48:15
%S A164109 3,2,4,6,9,6,9,7,0,1,1,3,3,4,1,4,5,7,4,5,4,8,0,1,1,0,8,9,6,2,3,5,0,3,
%T A164109 7,0,8,3,2,4,2,5,2,8,5,5,7,5,6,1,8,0,7,2,3,0,4,8,9,2,8,6,4,6,3,3,2,3,
%U A164109 6,1,8,4,8,5,6,0,9,0,6,5,3,9,6,7,0,7,2,8,9,0,7,8,2,5,0,9,9,7,5,1,6,9,8,9,7
%N A164109 Decimal expansion of Pi^4/3.
%C A164109 Surface area of the 8-dimensional unit sphere.
%H A164109 G. C. Greubel, <a href="/A164109/b164109.txt">Table of n, a(n) for n = 2..5000</a>
%H A164109 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Hypersphere.html">Hypersphere</a>.
%H A164109 Wikipedia, <a href="http://en.wikipedia.org/wiki/Hypersphere">Hypersphere</a>.
%H A164109 Ce Xu and Jianqiang Zhao, <a href="https://arxiv.org/abs/2203.04184">Sun's Three Conjectures on Apéry-like Sums Involving Harmonic Numbers</a>, arXiv:2203.04184 [math.NT], 2022.
%H A164109 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%F A164109 Equals 8*A164108 = A019670*A091925 = A092425/3.
%F A164109 Pi^4/30 = Sum_{k>=1} H(k)*H(k+1)/(k+1)^2, where H(k) = A001008(k)/A002805(k) is the k-th harmonic number. - _Amiram Eldar_, Aug 19 2025
%e A164109 32.4696970113341457454801108962350370832425285...
%t A164109 RealDigits[Pi^4/3,10,120][[1]] (* _Harvey P. Dale_, Jul 31 2014 *)
%o A164109 (PARI) Pi^4/3 \\ _G. C. Greubel_, Sep 11 2017
%Y A164109 Cf. A019692, A019694, A164102, A164104, A091925, A164107.
%Y A164109 Cf. A001008, A002805.
%K A164109 cons,nonn
%O A164109 2,1
%A A164109 _R. J. Mathar_, Aug 10 2009