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 A110032 #3 Mar 30 2012 18:59:08 %S A110032 1,-1,1,1,-3,1,0,5,-7,1,-4,22,23,-13,1,-64,20,172,29,-19,1,-240,-1120, %T A110032 -496,354,111,-29,1,2656,1760,-4952,-1816,1054,239,-41,1,15360,24800, %U A110032 -28640,-29040,2384,3938,203,-49,1,88064,587136,601216,-63776,-191224,-21360,6658,511,-65,1,-1714176,-4244224,4907392 %N A110032 A characteristic triangle for the Euler totient function (A000010). %C A110032 Form the n X n Hankel matrices phi(i-j+1), 1<=i,j<=n for the Euler totient function and take characteristic polynomials. Triangle rows give coefficients of the characteristic polynomials of these matrices. (Construction described by Michael Somos in A064831). First column is a signed version of Hankel transform of Euler totient function, A056229. %e A110032 Rows begin %e A110032 1; %e A110032 -1,1; %e A110032 1,-3,1; %e A110032 0,5,-7,1; %e A110032 -4,22,23,-13,1; %e A110032 -64,20,172,29,-19,1; %e A110032 -240,-1120,-496,354,111,-29,1; %K A110032 sign,tabl %O A110032 0,5 %A A110032 _Paul Barry_, Jul 08 2005