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A270758
Total sum of the sizes of all blocks with maximal element 4 in all set partitions of {1,2,...,n}.
3
30, 67, 195, 670, 2623, 11437, 54692, 283625, 1581303, 9413380, 59497049, 397402597, 2794008798, 20606565063, 158955946879, 1279119138486, 10712907438835, 93190762200361, 840437752639132, 7844783028326405, 75673025264120531, 753330825335964276
OFFSET
4,1
LINKS
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 *)
CROSSREFS
Column k=4 of A270701.
A diagonal of A270702.
Sequence in context: A219543 A309393 A154055 * A241192 A359545 A064623
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Mar 22 2016
STATUS
approved