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 A026052 #5 Dec 19 2012 15:50:09 %S A026052 2,6,13,22,35,52,74,100,132,170,215,266,325,392,468,552,646,750,865, %T A026052 990,1127,1276,1438,1612,1800,2002,2219,2450,2697,2960,3240,3536,3850, %U A026052 4182,4533,4902,5291,5700,6130,6580,7052,7546,8063,8602,9165,9752,10364,11000,11662,12350,13065,13806,14575 %N A026052 (d(n)-r(n))/2, where d = A008778 and r is the periodic sequence with fundamental period (1,1,0,1). %F A026052 a(n)=(n + 2)*(n^2 + 10*n + 15)/12 - 0.375 + 0.125*( - 1)^n - 0.25*cos(n*Pi/2) [From _Richard Choulet_, Dec 13 2008] %K A026052 nonn %O A026052 2,1 %A A026052 _Clark Kimberling_