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.

A111843 Matrix log of triangle A111840, 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 A111843 #7 Jun 13 2017 22:38:28
%S A111843 0,1,0,3,3,0,27,9,9,0,486,81,27,27,0,7776,1458,243,81,81,0,-2423196,
%T A111843 23328,4374,729,243,243,0,-97338996,-7269588,69984,13122,2187,729,729,
%U A111843 0,5883879500784,-292016988,-21808764,209952,39366,6561,2187,2187,0
%N A111843 Matrix log of triangle A111840, 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 A111843 Column k equals 3^k multiplied by column 0 (A111844) when ignoring zeros above the diagonal.
%F A111843 T(n, k) = 3^k*T(n-k, 0) = 3^k*A111844(n-k) for n>=k>=0.
%e A111843 Matrix log of A111840, with factorial denominators, begins:
%e A111843 0;
%e A111843 1/1!, 0;
%e A111843 3/2!, 3/1!, 0;
%e A111843 27/3!, 9/2!, 9/1!, 0;
%e A111843 486/4!, 81/3!, 27/2!, 27/1!, 0;
%e A111843 7776/5!, 1458/4!, 243/3!, 81/2!, 81/1!, 0;
%e A111843 -2423196/6!, 23328/5!, 4374/4!, 729/3!, 243/2!, 243/1!, 0;
%o A111843 (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,B[i,j]=1,if(j==1,B[i,j]=(A^q)[i-1,1], 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 A111843 Cf. A111840 (triangle), A111844 (column 0), A111815 (variant), A111941 (q=-1), A111810 (q=2), A111848 (q=4).
%K A111843 frac,sign,tabl
%O A111843 0,4
%A A111843 _Paul D. Hanna_, Aug 23 2005