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 A143808 #10 May 04 2024 14:29:55 %S A143808 1,1,1,1,2,2,1,2,4,5,1,2,4,10,12,1,2,4,10,24,29,1,2,4,10,24,58,70,1,2, %T A143808 4,10,24,58,140,169,1,2,4,10,24,58,140,338,408,1,2,4,10,24,58,140,338, %U A143808 816,985 %N A143808 Triangle read by rows, first n terms of the sequence (1, 2, 4, 10, ...) followed by P(n), where (2, 4, 10, 12, ...) = twice Pell numbers. %C A143808 Row sums = A000129(n), the Pell numbers: (1, 2, 5, 12, ...). %e A143808 First few rows of the triangle: %e A143808 1; %e A143808 1, 1; %e A143808 1, 2, 2; %e A143808 1, 2, 4, 5; %e A143808 1, 2, 4, 10, 12; %e A143808 1, 2, 4, 10, 24, 29; %e A143808 1, 2, 4, 10, 24, 58, 70; %e A143808 1, 2, 4, 10, 24, 58, 140, 169; %Y A143808 Cf. A000129. %K A143808 nonn,tabl %O A143808 0,5 %A A143808 _Gary W. Adamson_, Sep 01 2008