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 A026038 #8 Aug 09 2015 12:33:18 %S A026038 5,11,20,33,52,78,111,152,203,265,338,423,522,636,765,910,1073,1255, %T A026038 1456,1677,1920,2186,2475,2788,3127,3493,3886,4307,4758,5240,5753, %U A026038 6298,6877,7491,8140,8825,9548,10310,11111,11952,12835,13761,14730,15743,16802,17908,19061,20262,21513,22815,24168 %N A026038 a(n) = (d(n)-r(n))/2, where d = A026037 and r is the periodic sequence with fundamental period (1,0,0,1). %H A026038 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (4,-7,8,-7,4,-1). %F A026038 G.f. x^3*( 5-9*x+11*x^2-10*x^3+7*x^4-2*x^5 ) / ( (x^2+1)*(x-1)^4 ). - _R. J. Mathar_, Jun 22 2013 %K A026038 nonn %O A026038 3,1 %A A026038 _Clark Kimberling_