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 A087672 #2 Oct 12 2013 15:31:16 %S A087672 891,1485,1584,2376,3168,4455,4752,89991,95931,101871,107811,149985, %T A087672 155925,159984,161865,167805,167904,175824,183744,191664,239976, %U A087672 247896,255816,263736,271656,319968,327888,335808,343728,351648,449955,479655 %N A087672 n = k^2 - (reversal of k)^2 for two different values of k. %C A087672 Each n is a multiple of 99. The first few pairs for k: (30,54) (41,87) (40,53) (51,75) (62,97) (72,96) (71,84) (300,504) (310,534) (320,564) (330,594) (401,807) (411,837) (400,503) (421,867) (431,897) (410,523) (420,543) (430,563) (440,583). %e A087672 2376 = 51^2 - 15^2 = 75^2 - 57^2; 161865 = 421^2 - 124^2 = 867^2 - 768^2 %K A087672 nonn %O A087672 0,1 %A A087672 _Paul Lusch_, Sep 26 2003