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 A261540 #37 Sep 08 2022 08:46:13
%S A261540 0,29,478,4287,24476,101785,337434,946043,2333752,5206581,10714070,
%T A261540 20633239,37597908,65378417,109216786,176222355,275832944,420346573,
%U A261540 625528782,911300591,1302512140,1829807049,2530582538,3450050347,4642403496,6172093925,8115226054
%N A261540 a(n) = n^7 + 7*n^5 + 14*n^3 + 7*n.
%C A261540 Also numbers of the form (n-th metallic mean)^7 - 1/(n-th metallic mean)^7, see link to Wikipedia.
%H A261540 Raphael Ranna, <a href="/A261540/b261540.txt">Table of n, a(n) for n = 0..100</a>
%H A261540 Wikipedia, <a href="https://en.wikipedia.org/wiki/Metallic_mean">Metallic mean</a>
%H A261540 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (8,-28,56,-70,56,-28,8,-1).
%F A261540 a(n) = -a(-n) = ( (n+sqrt(n^2+4))/2 )^7 - 1/( (n+sqrt(n^2+4))/2 )^7.
%F A261540 G.f.: x*(29 + 246*x + 1275*x^2 + 1940*x^3 + 1275*x^4 + 246*x^5 + 29*x^6)/(1 - x)^8. - _Bruno Berselli_, Aug 24 2015
%t A261540 Table[n^7 + 7 n^5 + 14 n^3 + 7 n, {n, 0, 30}] (* _Bruno Berselli_, Aug 24 2015 *)
%t A261540 LinearRecurrence[{8, -28, 56, -70, 56, -28, 8, -1}, {0, 29, 478, 4287, 24476, 101785, 337434, 946043}, 30] (* _Vincenzo Librandi_, Aug 24 2015 *)
%o A261540 (Sage) [n^7+7*n^5+14*n^3+7*n for n in (0..30)] # _Bruno Berselli_, Aug 24 2015
%o A261540 (Magma) [n^7 + 7*n^5 + 14*n^3 + 7*n: n in [0..30]]; // _Vincenzo Librandi_, Aug 24 2015
%o A261540 (PARI) a(n)=n^7+7*n^5+14*n^3+7*n \\ _Charles R Greathouse IV_, Aug 24 2015
%Y A261540 Cf. A001622, A014176, A098316, A098317, A098318, A176398, A176439, A176458, A176522, A261391.
%K A261540 nonn,easy
%O A261540 0,2
%A A261540 _Raphael Ranna_, Aug 24 2015
%E A261540 Offset changed from 1 to 0 and initial 0 added by _Bruno Berselli_, Aug 25 2015