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 A097966 #14 Nov 09 2018 07:31:00 %S A097966 1,2,3,1,2,4,2,3,4,1,3,4,2,4,6,2,5,6,3,5,7,3,7,9,4,7,10,4,8,11,6,10, %T A097966 14,6,11,15,7,12,17,9,16,22,10,17,23,11,19,26,14,24,33,15,26,36,17,29, %U A097966 40,21,37,51,23,40,55,26,45,62,33,57,77,35,61,83 %N A097966 Rectangular array read by rows (n > 0, 1 <= k <= 3): T(n,k) = floor(b(n,k)/6^(2*(A002264(n) + 1)/3)), where b(n,k) = b(n-3,k) + 13*b (n-6,k) + 36*b(n-9,k), with initial values given in comments. %C A097966 From _Franck Maminirina Ramaharo_, Nov 08 2018: (Start) %C A097966 The initial values for b(n,k), 1 <= n <= 9, 1 <= k <= 3, are %C A097966 n\k | 1 2 3 %C A097966 ----+--------------- %C A097966 1 | 16 32 36 %C A097966 2 | 17 30 44 %C A097966 3 | 24 36 51 %C A097966 4 | 68 120 176 %C A097966 5 | 105 170 233 %C A097966 6 | 99 186 240 %C A097966 7 | 420 680 932 %C A097966 8 | 470 848 1129 %C A097966 9 | 519 870 1227. (End) %F A097966 From _Franck Maminirina Ramaharo_, Nov 08 2018: (Start) %F A097966 Let M and A denote the following 3 X 3 matrices: %F A097966 0, 4, 0 %F A097966 M = 1, 1, 3 %F A097966 3, 3, 0 %F A097966 and %F A097966 0, 1, 1 %F A097966 A = 1, 1, 2 %F A097966 1, 2, 2. %F A097966 Then applying floor() to the entries in (h*M)^(n + 1)*A, where h = 1/(6^(2/3)), yields row 3*n - 2 to 3*n. (End) %e A097966 Triangle begins: %e A097966 1, 2, 3; %e A097966 1, 2, 4; %e A097966 2, 3, 4; %e A097966 1, 3, 4; %e A097966 2, 4, 6; %e A097966 2, 5, 6; %e A097966 3, 5, 7; %e A097966 3, 7, 9; %e A097966 4, 7, 10; %e A097966 4, 8, 11; %e A097966 6, 10, 14; %e A097966 6, 11, 15; %e A097966 ... - _Franck Maminirina Ramaharo_, Nov 08 2018 %t A097966 M = N[(16/9)^(1/3)*({{0, 1, 0}, {1, 1, 0}, {0, 0, 0}}*(1/4) + {{0, 1, 0}, {0, 0, 1}, {1, 1, 0}}*(3/4))]; %t A097966 A[n_] := M.A[n - 1]; A[0] := {{0, 1, 1}, {1, 1, 2}, {1, 2, 2}}; %t A097966 Table[Floor[M.A[n]], {n, 1, 12}]//Flatten %Y A097966 Cf. A097964. %K A097966 nonn,tabf,less %O A097966 1,2 %A A097966 _Roger L. Bagula_, Sep 06 2004 %E A097966 Edited, new name, and offset corrected by _Franck Maminirina Ramaharo_, Nov 08 2018