A250105 Column 1 of triangle in A250104 (or A124323).

0, 0, 3, 4, 20, 66, 287, 1296, 6435, 34250, 194942, 1179036, 7544121, 50865920, 360167355, 2670210640, 20673196460, 166753291806, 1398415162703, 12169520162440, 109709590135635, 1022997624845614, 9852508254721222, 97880299543896216, 1001841501018883425

Offset: 1

Author

N. J. A. Sloane, Nov 16 2014

Keywords

• nonn

Links

• T. Mansour, A. O. Munagi, Set partitions with circular successions, European Journal of Combinatorics, 42 (2014), 207-216.

Crossrefs

Cf. A250104, A124323.

Programs

Mathematica

a[n_] := n*(Sum[(-1)^(j-1)*BellB[n-j-1], {j, 1, n-1}]-(-1)^n); a[1] = 0; Table[a[n], {n, 1, 25}] (* Jean-François Alcover, Dec 09 2014 *)