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 A115025 #8 Feb 26 2015 09:32:08 %S A115025 1,2,2,7,3,21,25,113,17,289,321,1665,769,5633,7169,30721,2049,69633, %T A115025 73729,409601,163841,1376257,1703937,7602177,1572865,19922945, %U A115025 23068673,113246209,58720257,385875969,503316481,2080374785,67108865,4429185025,4563402753 %N A115025 a(n) = n-th element of n-th row of triangle shown below. %C A115025 1 %C A115025 1..............................................2 %C A115025 1......................3.......................2.......................4 %C A115025 1...........5..........3...........7...........2...........6...........4...........8 %C A115025 1.....9.....5....13....3....11.....7....15.....2....10.....6....14.....4....12.....8....16 %C A115025 1.17..9.25..5.21.13.29.3.19.11.27..7.23.15.31..2.18.10.26..6.22.14.30..4.20.12.28..8.24.16.32 %C A115025 ... %H A115025 Alois P. Heinz, <a href="/A115025/b115025.txt">Table of n, a(n) for n = 1..1000</a> %Y A115025 Cf. A049773. %K A115025 nonn %O A115025 1,2 %A A115025 _Jonas Wallgren_, Feb 24 2006 %E A115025 Offset changed to 1 by _Alois P. Heinz_, Feb 26 2015 %E A115025 a(16)-a(35) from _Alois P. Heinz_, Feb 26 2015