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 A131327 #4 Aug 13 2012 06:54:19 %S A131327 1,3,1,1,3,1,3,5,3,1,1,3,9,3,1,3,9,3,13,3,1,1,3,21,3,17,3,1,3,13,3,37, %T A131327 3,21,3,1,1,3,37,3,57,3,25,3,1,3,17,3,77,3,81,3,29,3,1,1,3,57,3,137,3, %U A131327 109,3,33,3,1,3,21,3,137,3,221,3,141,3,37,3,1,1,3,81,3,277,3,333,3,177 %N A131327 Triangle |4*|A049310(n,k)| - 3| read by rows, 0<=k<=n. %e A131327 First few rows of the triangle are: %e A131327 1; %e A131327 3, 1; %e A131327 1, 3, 1; %e A131327 3, 5, 3, 1; %e A131327 1, 3, 9, 3, 1; %e A131327 3, 9, 3, 13, 3, 1; %e A131327 1, 3, 21, 3, 17, 3, 1; %e A131327 ... %p A131327 A131327 := proc(n,k) %p A131327 abs(4*abs(A049310(n,k))-3) ; %p A131327 end proc: %p A131327 seq(seq(A131327(n,k),k=0..n),n=0..12) ; # _R. J. Mathar_, Aug 13 2012 %Y A131327 Cf. A049310, A131328 (row sums), A131324, A131325, A131326. %K A131327 nonn,tabl %O A131327 0,2 %A A131327 _Gary W. Adamson_, Jun 28 2007 %E A131327 Definition corrected. - _R. J. Mathar_, Aug 13 2012