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 A017121 #17 Apr 25 2023 03:26:36
%S A017121 262144,5159780352,512000000000,10578455953408,101559956668416,
%T A017121 618121839509504,2779905883635712,10077696000000000,31087100296429568,
%U A017121 84590643846578176,208215748530929664,472161363286556672,1000000000000000000,1999004627104432128,3802961274698203136
%N A017121 a(n) = (8*n + 4)^9.
%H A017121 Vincenzo Librandi, <a href="/A017121/b017121.txt">Table of n, a(n) for n = 0..10000</a>
%H A017121 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (10,-45,120,-210,252,-210,120,-45,10,-1).
%F A017121 G.f.: 262144*(1+x)*(x^8 + 19672*x^7 + 1736668*x^6 + 19971304*x^5 + 49441990*x^4 + 19971304*x^3 + 1736668*x^2 + 19672*x + 1) / (x-1)^10 . - _R. J. Mathar_, May 08 2015
%F A017121 From _Amiram Eldar_, Apr 25 2023: (Start)
%F A017121 a(n) = A017113(n)^9.
%F A017121 a(n) = 2^9*A016833(n) = 2^18*A016761(n).
%F A017121 Sum_{n>=0} 1/a(n) = 511*zeta(9)/134217728.
%F A017121 Sum_{n>=0} (-1)^n/a(n) = 277*Pi^9/2164663517184. (End)
%t A017121 Table[(8*n + 4)^9, {n, 0, 20}] (* _Amiram Eldar_, Apr 25 2023 *)
%o A017121 (Magma) [(8*n+4)^9: n in [0..15] ]; // _Vincenzo Librandi_, Jul 21 2011
%Y A017121 Cf. A013667, A016761, A016833, A017113.
%K A017121 nonn,easy
%O A017121 0,1
%A A017121 _N. J. A. Sloane_