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 A138272 #2 Mar 30 2012 18:37:09 %S A138272 1,1,4,28,268,3164,43672,682632,11834536,224283416,4597330748, %T A138272 101100605540,2370095338372,58924635472260,1546999678599872, %U A138272 42734731811302304,1238309697485975648,37538075865014728096 %N A138272 Column 0 of triangle A138271; also, column 3 of A138271 shift left; also, column 0 of matrix power A138271^4 shift right. %Y A138272 Cf. A138271; A138273, A138274; A138275. %K A138272 nonn %O A138272 0,3 %A A138272 _Paul D. Hanna_, Mar 11 2008