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 A361952 #10 Apr 01 2023 14:27:39 %S A361952 1,1,0,1,1,0,1,2,1,0,1,3,4,1,0,1,4,8,8,1,0,1,5,13,21,17,1,0,1,6,19,40, %T A361952 58,38,1,0,1,7,26,66,126,172,94,1,0,1,8,34,100,228,420,569,258,1,0,1, %U A361952 9,43,143,373,816,1537,2148,815,1,0,1,10,53,196,571,1412,3140,6342,9538,3038,1,0 %N A361952 Array read by antidiagonals: T(n,k) is the number of unlabeled posets with n elements together with a function rk mapping each element to a rank between 1 and k such that whenever v covers w in the poset then rk(v) = rk(w) + 1. %C A361952 A poset is counted once for each admissible ranking function. This is an intermediate step in the computation of A361953 where each graded poset is counted exactly once. %H A361952 Andrew Howroyd, <a href="/A361952/b361952.txt">Table of n, a(n) for n = 0..860</a> (first 41 antidiagonals). %e A361952 Array begins: %e A361952 ============================================ %e A361952 n/k| 0 1 2 3 4 5 6 7 ... %e A361952 ---+---------------------------------------- %e A361952 0 | 1 1 1 1 1 1 1 1 ... %e A361952 1 | 0 1 2 3 4 5 6 7 ... %e A361952 2 | 0 1 4 8 13 19 26 34 ... %e A361952 3 | 0 1 8 21 40 66 100 143 ... %e A361952 4 | 0 1 17 58 126 228 373 571 ... %e A361952 5 | 0 1 38 172 420 816 1412 2272 ... %e A361952 6 | 0 1 94 569 1537 3140 5631 9351 ... %e A361952 7 | 0 1 258 2148 6342 13383 24410 41097 ... %e A361952 ... %o A361952 (PARI) \\ See Links in A361953 for program. %o A361952 { my(A=A361952tabl(7)); for(i=1, #A, print(A[i,])) } %Y A361952 Columns k=0..2 are A000007, A000012, A049312. %Y A361952 Rows n=0..4 are A000012, A000027, A034856, A137742. %Y A361952 The labeled version is A361950. %Y A361952 Cf. A361953. %K A361952 nonn,tabl %O A361952 0,8 %A A361952 _Andrew Howroyd_, Mar 31 2023