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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.

A103237 Triangular matrix T, read by rows, that satisfies: T^3 + 3T^2 + 3T = SHIFTUP(T), also T^(n+2) + 3T^(n+1) + 3T^n = SHIFTUP(T^n - D*T^(n-1)) for all n, where D is a diagonal matrix with diagonal(D) = diagonal(T) = {1,2,3,...}.

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%I A103237 #11 Jul 20 2024 18:42:51
%S A103237 1,7,2,133,26,3,5362,962,63,4,380093,66794,3843,124,5,42258384,
%T A103237 7380100,409248,11284,215,6,6830081860,1190206134,65160081,1709836,
%U A103237 27305,342,7,1520132414241,264665899160,14416260516,371199704,5585270,57798,511,8
%N A103237 Triangular matrix T, read by rows, that satisfies: T^3 + 3T^2 + 3T = SHIFTUP(T), also T^(n+2) + 3T^(n+1) + 3T^n = SHIFTUP(T^n - D*T^(n-1)) for all n, where D is a diagonal matrix with diagonal(D) = diagonal(T) = {1,2,3,...}.
%C A103237 Leftmost column is A082164 (enumerates acyclic automata with 3 inputs). The operation SHIFTUP(T) shifts each column of T up 1 row, dropping the elements that occupied the diagonal of T.
%F A103237 T = P*D*P^-1 where P(r, c) = A103248(r, c)/(r-c)! = (-1)^(r-c)*(c^3+3*c^2+3*c)^(r-c)/(r-c)! for r>=c>=1 and [P^-1](r, c) = A103243(r, c)/(r-c)! and D is a diagonal matrix = {1, 2, 3, ...}.
%e A103237 Rows of T begin:
%e A103237 [1],
%e A103237 [7,2],
%e A103237 [133,26,3],
%e A103237 [5362,962,63,4],
%e A103237 [380093,66794,3843,124,5],
%e A103237 [42258384,7380100,409248,11284,215,6],
%e A103237 [6830081860,1190206134,65160081,1709836,27305,342,7],...
%e A103237 Rows of T^2 begin:
%e A103237 [1],
%e A103237 [21,4],
%e A103237 [714,130,9],
%e A103237 [41923,7410,441,16],...
%e A103237 Rows of T^3 begin:
%e A103237 [1],
%e A103237 [49,8],
%e A103237 [2821,494,27],
%e A103237 [238238,41678,2331,64],...
%e A103237 Rows of T^3 + 3*T^2 + 3*T equals SHIFTUP(T):
%e A103237 [7],
%e A103237 [133,26],
%e A103237 [5362,962,63],
%e A103237 [380093,66794,3843,124],...
%o A103237 (PARI) {T(n,k)=local(P,D);D=matrix(n+1,n+1,r,c,if(r==c,r)); P=matrix(n+1,n+1,r,c,if(r>=c,(-1)^(r-c)*(c^3+3*c^2+3*c)^(r-c)/(r-c)!)); return(if(n<k||k<0,0,(P*D*P^-1)[n+1,k+1]))}
%Y A103237 Cf. A082164, A103248, A103243, A103236.
%K A103237 nonn,tabl
%O A103237 0,2
%A A103237 _Paul D. Hanna_, Jan 31 2005