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 A350772 #10 Feb 11 2022 17:14:01 %S A350772 1,1,1,3,1,1,9,4,1,1,30,12,4,1,1,103,45,13,4,1,1,375,160,48,13,4,1,1, %T A350772 1400,613,175,49,13,4,1,1,5380,2354,680,178,49,13,4,1,1 %N A350772 Triangle read by rows: T(n,k) is the number of n-element unlabeled series-parallel posets with k connected components. %e A350772 Triangle begins: %e A350772 1; %e A350772 1, 1; %e A350772 3, 1, 1; %e A350772 9, 4, 1, 1; %e A350772 30, 12, 4, 1, 1; %e A350772 103, 45, 13, 4, 1, 1; %e A350772 375, 160, 48, 13, 4, 1, 1; %e A350772 1400, 613, 175, 49, 13, 4, 1, 1; %e A350772 5380, 2354, 680, 178, 49, 13, 4, 1, 1; %e A350772 ... %Y A350772 Row sums give A003430. %Y A350772 Column 1 is A007453. %Y A350772 Cf. A263864 (all posets), A349488 (disconnected). %K A350772 nonn,tabl %O A350772 1,4 %A A350772 _Salah Uddin Mohammad_, Jan 14 2022