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 A174163 #5 Mar 30 2012 18:40:08 %S A174163 1,3,6,10,15,21,35,55,66,78,104,136,153,171,209,253,322,406,435,465, %T A174163 558,666,740,820,861,903,989,1081,1222,1378,1537,1711,1770,1830,2013, %U A174163 2211,2345,2485,2556,2628,2847,3081,3239,3403,3652,3916,4272,4656,4850,5050,5151,5253 %N A174163 a(n) = (A173919(k)*A173919(k+1))/2. %C A174163 Triangular numbers are (n*(n+1))/2 with n or n+1 twin prime %C A174163 a(n)+a(n+1) is square: 1,4,9,16,25,36,121,144,289,324... %Y A174163 Cf. A173919 %K A174163 nonn %O A174163 1,2 %A A174163 _Giovanni Teofilatto_, Mar 10 2010 %E A174163 Corrected definition and insert a comment _Giovanni Teofilatto_, Apr 13 2010 %E A174163 Corrected definition and extended _Giovanni Teofilatto_, Apr 14 2010 %E A174163 Missing numbers (35, 104 etc.) inserted by _R. J. Mathar_, Aug 23 2010