A007975 - OEIS

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A007975

Number of permutations that are 3 "block reversals" away from 12...n.

4

2, 55, 389, 1563, 4642, 11407, 24600, 48204, 87758, 150707, 246787, 388445, 591294, 874603, 1261822, 1781142, 2466090, 3356159, 4497473, 5943487, 7755722, 10004535, 12769924, 16142368, 20223702, 25128027, 30982655, 37929089, 46124038, 55740467

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OFFSET

4,1

LINKS

Table of n, a(n) for n=4..33.

CROSSREFS

Cf. A007972, A007973, A007974.

Column k=3 of A300003.

Sequence in context: A356985 A280209 A157262 * A109796 A186886 A024029

Adjacent sequences: A007972 A007973 A007974 * A007976 A007977 A007978

KEYWORD

nonn

AUTHOR

EXTENSIONS

More terms from Sean A. Irvine, Feb 22 2018

STATUS

approved