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 A115691 #6 Mar 30 2012 17:40:35 %S A115691 1,100,1000,5400,10000,54000,100000,540000,1000000,1306449,1728243, %T A115691 5400000,10000000,50086125,54000000,100000000,130644900,172824300, %U A115691 540000000,1000000000,1044000721,1306449000,1728243000,5008612500 %N A115691 Powerful(1) numbers (A001694) whose digit reversal is a triangular number. %H A115691 <a href="/index/Pow#powerful">Index entries for sequences related to powerful numbers</a> %e A115691 5400=2^3*3^3*5^2 is powerful and 45=T(9). %Y A115691 Cf. A001694, A115692. %K A115691 nonn,base %O A115691 1,2 %A A115691 _Giovanni Resta_, Jan 31 2006 %E A115691 a(14)-a(24) from _Donovan Johnson_, Oct 01 2009