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 A131230 #8 Jun 08 2023 04:43:29
%S A131230 1,4,1,5,2,1,8,1,2,1,9,2,1,2,1,12,1,2,1,2,1,13,2,1,2,1,2,1,16,1,2,1,2,
%T A131230 1,2,1,17,2,1,2,1,2,1,2,1,20,1,2,1,2,1,2,1,2,1,21,2,1,2,1,2,1,2,1,2,1,
%U A131230 24,1,2,1,2,1,2,1,2,1,2,1,25,2,1,2,1,2,1,2,1,2,1,2,1
%N A131230 Triangle read by rows: 2*A130296 - A128174.
%C A131230 Left column = A042948, numbers congruent to {1,0} mod 4: (1, 4, 5, 8, 9, 12, ...).
%C A131230 Row sums = A047383, numbers congruent to {1,5} mod 7: (1, 5, 8, 12, 15, ...).
%e A131230 First few rows of the triangle:
%e A131230 1;
%e A131230 4, 1;
%e A131230 5, 2, 1;
%e A131230 8, 1, 2, 1;
%e A131230 9, 2, 1, 2, 1;
%e A131230 12, 1, 2, 1, 2, 1;
%e A131230 ...
%Y A131230 Cf. A047383, A042948, A128174, A131231, A130296.
%K A131230 nonn,tabl
%O A131230 1,2
%A A131230 _Gary W. Adamson_, Jun 20 2007
%E A131230 Incorrect formula removed and more terms from _Georg Fischer_, Jun 08 2023