A270758 Total sum of the sizes of all blocks with maximal element 4 in all set partitions of {1,2,...,n}.

30, 67, 195, 670, 2623, 11437, 54692, 283625, 1581303, 9413380, 59497049, 397402597, 2794008798, 20606565063, 158955946879, 1279119138486, 10712907438835, 93190762200361, 840437752639132, 7844783028326405, 75673025264120531, 753330825335964276

Offset: 4

Author

Alois P. Heinz, Mar 22 2016

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 4..577
• Wikipedia, Partition of a set

Crossrefs

Column k=4 of A270701.

A diagonal of A270702.

Programs

Mathematica

b[n_, m_, t_] := b[n, m, t] = If[n == 0, {1, 0}, Sum[If[t == 1 && j != m + 1, 0, Function[p, p + If[j == -t || t == 1 && j == m + 1, {0, p[[1]]}, 0]][b[n - 1, Max[m, j], If[t == 1 && j == m + 1, -j, If[t < 0, t, If[t > 0, t - 1, 0]]]]]], {j, 1, m + 1}]];
a[n_] := b[n, 0, Max[0, 1 + n - 4]][[2]];
Array[a, 24, 4] (* Jean-François Alcover, May 26 2018, from Maple code for A270701 *)