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A225963 Number of permutations of [n] having exactly 2 strong fixed blocks. 2
1, 5, 25, 134, 815, 5657, 44549, 394266, 3883182, 42174500, 500942458, 6460077110, 89875729761, 1341559805867, 21382747361727, 362402701510514, 6507348542427217, 123394642353693319, 2463866954996239829, 51670868533003154264, 1135456889195715187948 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,2

COMMENTS

See A186373 for the definition of strong fixed blocks.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 4..450

FORMULA

a(n) ~ n! / n^2. - Vaclav Kotesovec, Aug 29 2014

CROSSREFS

Column k=2 of A186373.

Sequence in context: A351187 A344396 A351587 * A222570 A344268 A144818

Adjacent sequences:  A225960 A225961 A225962 * A225964 A225965 A225966

KEYWORD

nonn

AUTHOR

Alois P. Heinz, May 22 2013

STATUS

approved

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Last modified May 19 04:20 EDT 2022. Contains 353826 sequences. (Running on oeis4.)