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 A171172 #4 Mar 30 2012 17:34:03 %S A171172 1,1,4,1,2,3,7,1,2,3,4,5,10,1,2,3,4,5,6,7,13,1,2,3,4,5,6,7,8,9,16,1,2, %T A171172 3,4,5,6,7,8,9,10,11,19,1,2,3,4,5,6,7,8,9,10,11,12,13,22,1,2,3,4,5,6, %U A171172 7,8,9,10,11,12,13,14,15,25,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,28,1 %N A171172 Triangle read by rows in which row n lists 3n-2 together with the first 2n-1 positive integers. %e A171172 Triangle begins: %e A171172 1,1, %e A171172 4,1,2,3, %e A171172 7,1,2,3,4,5, %e A171172 10,1,2,3,4,5,6,7, %e A171172 13,1,2,3,4,5,6,7,8,9, %e A171172 16,1,2,3,4,5,6,7,8,9,10,11, %e A171172 19,1,2,3,4,5,6,7,8,9,10,11,12,13, %e A171172 22,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15, %e A171172 25,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17, %Y A171172 Cf. A016777, A172310, A171173, A171174, A171175, A171176, A171177, A171178. %K A171172 easy,nonn,tabf %O A171172 1,3 %A A171172 _Omar E. Pol_, Feb 23 2010