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 A179430 #2 Mar 30 2012 18:37:22 %S A179430 1,1,1,3,9,1,84,405,81,1,17550,121500,32805,729,1,25621596,247203171, %T A179430 82255257,2539107,6561,1,268715232324,3543210805275,1382411964132, %U A179430 53628242751,199290375,59049,1,21091830512086620,373203783345533355 %N A179430 Triangular matrix T where column 0 of T^m equals C(m*3^(n-1), n) at row n for n>=0, m>=0. %e A179430 Triangle T begins: %e A179430 1; %e A179430 1, 1; %e A179430 3, 9, 1; %e A179430 84, 405, 81, 1; %e A179430 17550, 121500, 32805, 729, 1; %e A179430 25621596, 247203171, 82255257, 2539107, 6561, 1; %e A179430 268715232324, 3543210805275, 1382411964132, 53628242751, 199290375, 59049, 1; %e A179430 21091830512086620, 373203783345533355, 165018275857291311, 7607829219099993, 36456526295226, 15884240049, 531441, 1; ... %e A179430 where column 0 of T equals A179431(n) = C(3^(n-1), n): %e A179430 [1, 1, 3, 84, 17550, 25621596, 268715232324, ...]. ... %e A179430 Illustrate row n in column 0 of T^m equals C(m*3^(n-1), n) as follows. %e A179430 Matrix square T^2 begins: %e A179430 1; %e A179430 2, 1; %e A179430 15, 18, 1; %e A179430 816, 1539, 162, 1; %e A179430 316251, 833490, 124659, 1458, 1; %e A179430 873642672, 3060203490, 585411786, 9861183, 13122, 1; ... %e A179430 where column 0 of T^2 equals A179432(n) = C(2*3^(n-1), n): %e A179430 [1, 2, 15, 816, 316251, 873642672, 17743125256857, ...]. ... %e A179430 Matrix cube T^3 begins: %e A179430 1; %e A179430 3, 1; %e A179430 36, 27, 1; %e A179430 2925, 3402, 243, 1; %e A179430 1663740, 2667411, 275562, 2187, 1; %e A179430 6774333588, 14164214850, 1896890076, 21966228, 19683, 1; ... %e A179430 where column 0 of T^3 equals A136393(n) = C(3^n, n): %e A179430 [1, 3, 36, 2925, 1663740, 6774333588, 204208594169580, ...]. %o A179430 (PARI) {T(n, k)=local(M=matrix(n+1, n+1, r, c, binomial(r*3^(c-2), c-1)), P); P=matrix(n+1, n+1, r, c, binomial((r+1)*3^(c-2), c-1)); (P~*M~^-1)[n+1, k+1]} %Y A179430 Cf. A179431, A179432, A136393, A179433, A179434, variant: A136467. %K A179430 nonn,tabl %O A179430 0,4 %A A179430 _Paul D. Hanna_, Jul 20 2010