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 A117398 #8 Sep 07 2022 04:08:09 %S A117398 0,1,0,0,2,0,-1,2,3,0,-3,4,5,4,0,-9,14,15,9,5,0,-33,68,65,34,14,6,0, %T A117398 -153,404,359,174,63,20,7,0,-873,2804,2375,1098,371,104,27,8,0,-5913, %U A117398 22244,18215,8154,2639,692,159,35,9,0,-46233,198644,158615,69354,21791,5480,1179,230,44,10,0 %N A117398 Matrix log of triangle A117396. %C A117398 Column 0 contains negative of sequence A007489. %H A117398 G. C. Greubel, <a href="/A117398/b117398.txt">Rows n = 0..50 of the triangle, flattened</a> %F A117398 From _G. C. Greubel_, Sep 06 2022: (Start) %F A117398 T(n, n) = 0. %F A117398 T(n, n-1) = A000027(n). %F A117398 T(n, n-2) = A000096(n-2). %F A117398 T(n, 0) = n*[n<2] - A007489(n-2)*[n>1]. %F A117398 T(n, 1) = 0 + 2*A117399(n-1)*[n>1]. %F A117398 Sum_{k=0..n} T(n, k) = A003422(n). (End) %e A117398 Triangle begins: %e A117398 0; %e A117398 1, 0; %e A117398 0, 2, 0; %e A117398 -1, 2, 3, 0; %e A117398 -3, 4, 5, 4, 0; %e A117398 -9, 14, 15, 9, 5, 0; %e A117398 -33, 68, 65, 34, 14, 6, 0; %e A117398 -153, 404, 359, 174, 63, 20, 7, 0; %e A117398 -873, 2804, 2375, 1098, 371, 104, 27, 8, 0; %e A117398 -5913, 22244, 18215, 8154, 2639, 692, 159, 35, 9, 0; %t A117398 m=12; %t A117398 M= Table[If[k>n-1, 0, If[k==n-1, n, -1]], {n,0,m+1}, {k,0,m+1}]; %t A117398 T:= T= Sum[MatrixPower[M, j]/j, {j,m+1}]; %t A117398 Table[T[[n+1, k+1]], {n,0,m}, {k,0,n}]//Flatten (* _G. C. Greubel_, Sep 06 2022 *) %o A117398 (PARI) {T(n,k)=local(M=matrix(n+4,n+4,r,c,if(r>=c,if(r==c+1,-c,1))), L=sum(m=1,n+4,(M^0-M)^m/m));L[n+1,k+1]} %Y A117398 Cf. A117396, A007489 (column 0), A117399 (column 1). %Y A117398 Cf. A000027, A000096, A003422. %K A117398 sign,tabl %O A117398 0,5 %A A117398 _Paul D. Hanna_, Mar 11 2006