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 A143120 #5 Dec 29 2023 10:27:25 %S A143120 1,1,2,3,4,5,2,5,6,7,5,7,10,11,12,3,8,10,13,14,15,7,10,15,17,20,21,22, %T A143120 4,11,19,21,24,25,26,9,13,20,23,28,30,33,34,35,5,14,18,25,28,33,35,38, %U A143120 39,40,11,16,25,29,36,39,44,49,50,51,6,17,22,31,35,42,45,50,52,55,56,57 %N A143120 A000012 * (A026741 * 0^(n-k)) * A000012, 1<=k<=n. %C A143120 Left border = A026741: (1, 1, 3, 2, 5, 3, 7, 4, 9,...). %C A143120 Right border = A001318 starting (1, 2, 5, 7, 12, 15,...). %C A143120 Row sums = A122576, unsigned: (1, 3, 12, 20, 45, 63, 112,...). %F A143120 A000012 * (A026741 * 0^(n-k)) * A000012, 1<=k<=n %e A143120 First few rows of the triangle are: %e A143120 1; %e A143120 1, 2; %e A143120 3, 4, 5; %e A143120 2, 5, 6, 7; %e A143120 5, 7, 10, 11, 12; %e A143120 3, 8, 10, 13, 14, 15; %e A143120 7, 10, 15, 17, 20, 21, 22; %e A143120 4, 11, 14, 19, 21, 24, 25, 26; %e A143120 ... %Y A143120 Cf. A026741, A001318, A122576. %K A143120 nonn,tabl %O A143120 1,3 %A A143120 _Gary W. Adamson_ & _Roger L. Bagula_, Jul 26 2008