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 A219527 #19 Apr 01 2018 13:23:36
%S A219527 1,3,11,19,37,55,87,119,169,219,291,363,461,559,687,815,977,1139,1339,
%T A219527 1539,1781,2023,2311,2599,2937,3275,3667,4059,4509,4959,5471,5983,
%U A219527 6561,7139,7787,8435,9157,9879,10679,11479,12361,13243
%N A219527 a(n) = (6*n^2 + 7*n - 9 + 2*n^3)/12 - (-1)^n*(n+1)/4.
%C A219527 First column of the Mendeleyev-Moseley-Seaborg table (with alkali metals) or 31st column of the Janet table. See A138726.
%C A219527 (a(n+10) - a(n))/10 = 29, 36, 45, 54, ... = A061925(n+7) + 3.
%C A219527 b(n) = a(n+1) - 2*a(n) = 1, 5, -3, -1, -19, -23, -55, -69, -119, -147, -219, -265, -363, -431, ... contains -a(2*n).
%C A219527 b(2*n-1) - b(2*n-2) = 4, 2, -4, -14, -28, -46, -68, ... = A147973(n+3).
%H A219527 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,-4,1,2,-1).
%F A219527 a(n) = A168380(n+1) - 1.
%F A219527 a(n+2) - a(n+1) = A093907(n) = A137583(n+1).
%F A219527 a(n+3) - a(n+1) = 10,16,26,36,... = A137928(n+3).
%F A219527 G.f. x*(1 + x + 4*x^2 - 2*x^3 + x^5 - x^4) / ( (1+x)^2*(x-1)^4 ). - _R. J. Mathar_, Mar 27 2013
%t A219527 a[n_] := (6*n^2 + 7*n - 9 + 2*n^3)/12 - (-1)^n*(n + 1)/4; Table[ a[n], {n, 1, 42}] (* _Jean-François Alcover_, Apr 05 2013 *)
%t A219527 LinearRecurrence[{2,1,-4,1,2,-1},{1,3,11,19,37,55},50] (* _Harvey P. Dale_, Apr 01 2018 *)
%Y A219527 Cf. A147973.
%K A219527 nonn,easy
%O A219527 1,2
%A A219527 _Paul Curtz_, Nov 21 2012