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 A124390 #3 Mar 30 2012 18:59:18 %S A124390 1,2,3,4,7,12,23,46,97,212,481,1124,2705,6682,16919,43840,116087, %T A124390 313764,864683,2427306,6934769,20148124,59486997,178364624,542790609, %U A124390 1675526482,5243746235,16630136364,53422028679,173754047228 %N A124390 Antidiagonal sums of square array A124389. %F A124390 Sums of antidiagonals of a Kolakoski related square array. %K A124390 nonn %O A124390 0,2 %A A124390 _Paul Barry_, Oct 30 2006