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 A248423 #15 Oct 07 2014 20:35:51 %S A248423 0,4,8,21,61,2,42,82,23,63,4,44,84,25,65,6,46,86,27,67,8,48,88,29,69, %T A248423 1,401,801,211,611,21,421,821,231,631,41,441,841,251,651,61,461,861, %U A248423 271,671,81,481,881,291,691,2 %N A248423 Multiples of 4 with digits backwards. %o A248423 (PARI) a(n) = subst(Polrev(digits(4*n)), x, 10); \\ _Michel Marcus_, Oct 06 2014 %Y A248423 Cf. A004093 (multiples of 2 backwards), A008586 (multiples of 4). %K A248423 nonn,base %O A248423 0,2 %A A248423 _Jacy Fang_, Oct 06 2014