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 A286416 #17 Aug 03 2021 15:02:23 %S A286416 1,3,1,8,6,1,24,25,10,1,83,98,63,15,1,324,399,338,135,21,1,1400,1746, %T A286416 1727,980,257,28,1,6609,8271,8874,6426,2455,448,36,1,33758,42284, %U A286416 47191,40334,20506,5474,730,45,1,185136,231939,263458,250839,158827,57239,11128,1128,55,1 %N A286416 Number T(n,k) of entries in the k-th last blocks of all set partitions of [n]; triangle T(n,k), n>=1, 1<=k<=n, read by rows. %H A286416 Alois P. Heinz, <a href="/A286416/b286416.txt">Rows n = 1..141, flattened</a> %H A286416 Wikipedia, <a href="https://en.wikipedia.org/wiki/Partition_of_a_set">Partition of a set</a> %e A286416 T(3,2) = 6 because the number of entries in the second last blocks of all set partitions of [3] (123, 12|3, 13|2, 1|23, 1|2|3) is 0+2+2+1+1 = 6. %e A286416 Triangle T(n,k) begins: %e A286416 1; %e A286416 3, 1; %e A286416 8, 6, 1; %e A286416 24, 25, 10, 1; %e A286416 83, 98, 63, 15, 1; %e A286416 324, 399, 338, 135, 21, 1; %e A286416 1400, 1746, 1727, 980, 257, 28, 1; %e A286416 6609, 8271, 8874, 6426, 2455, 448, 36, 1; %e A286416 ... %Y A286416 Columns k=1-2 give: A038561 (for n>1), A286433. %Y A286416 Main diagonal and first lower diagonal give: A000012, A000217. %Y A286416 Row sums give A070071. %Y A286416 Cf. A000110, A130534, A270236, A286232. %K A286416 nonn,tabl %O A286416 1,2 %A A286416 _Alois P. Heinz_, May 08 2017