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 A214446 #15 Jun 02 2025 08:05:17 %S A214446 -2,-2,6,28,70,138,238,376,558,790,1078,1428,1846,2338,2910,3568,4318, %T A214446 5166,6118,7180,8358,9658,11086,12648,14350,16198,18198,20356,22678, %U A214446 25170,27838,30688,33726,36958,40390,44028,47878 %N A214446 n*(n^2-2*n-1). %H A214446 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1). %F A214446 a(n) = -2*A110427(n). G.f. 2*x*(-1+3*x+x^2) / (x-1)^4 . - _R. J. Mathar_, Jul 18 2012 %o A214446 (PARI) a(n) = n*(n^2 - 2*n - 1) \\ _Michel Marcus_, Jul 15 2013 %K A214446 sign,easy %O A214446 1,1 %A A214446 _Marco Piazzalunga_, Jul 18 2012