cp's OEIS Frontend

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.

A111815 Matrix log of triangle A078122, which shifts columns left and up under matrix cube; these terms are the result of multiplying each element in row n and column k by (n-k)!.

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%I A111815 #8 Jun 13 2017 22:33:49
%S A111815 0,1,0,-1,3,0,-3,-3,9,0,150,-9,-9,27,0,1236,450,-27,-27,81,0,-2555748,
%T A111815 3708,1350,-81,-81,243,0,-64342116,-7667244,11124,4050,-243,-243,729,
%U A111815 0,5885700899760,-193026348,-23001732,33372,12150,-729,-729,2187,0
%N A111815 Matrix log of triangle A078122, which shifts columns left and up under matrix cube; these terms are the result of multiplying each element in row n and column k by (n-k)!.
%C A111815 Column k equals 3^k multiplied by column 0 (A111816) when ignoring zeros above the diagonal.
%F A111815 T(n, k) = 3^k*T(n-k, 0) = A111816(n-k) for n>=k>=0.
%e A111815 Matrix log of A078122, with factorial denominators, begins:
%e A111815 0;
%e A111815 1/1!, 0;
%e A111815 -1/2!, 3/1!, 0;
%e A111815 -3/3!, -3/2!, 9/1!, 0;
%e A111815 150/4!, -9/3!, -9/2!, 27/1!, 0;
%e A111815 1236/5!, 450/4!, -27/3!, -27/2!, 81/1!, 0;
%e A111815 -2555748/6!, 3708/5!, 1350/4!, -81/3!, -81/2!, 243/1!, 0; ...
%o A111815 (PARI) T(n,k,q=3)=local(A=Mat(1),B);if(n<k || k<0,0, for(m=1,n+1,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i || j==1,B[i,j]=1,B[i,j]=(A^q)[i-1,j-1]);));A=B); B=sum(i=1,#A,-(A^0-A)^i/i);return((n-k)!*B[n+1,k+1]))
%Y A111815 Cf. A078122, A111816 (column 0), A111840 (variant); log matrices: A110504 (q=-1), A111813 (q=2), A111818 (q=4), A111823 (q=5), A111828 (q=6), A111833 (q=7), A111838 (q=8).
%K A111815 frac,sign,tabl
%O A111815 0,5
%A A111815 _Gottfried Helms_ and _Paul D. Hanna_, Aug 22 2005