A246251 Number of permutations of [n] with exactly six occurrences of the consecutive step pattern up, down, down.

1488257158851, 176902009674966, 13166075391964578, 775944032960346939, 39844140679287441918, 1872063201155821139178, 82897279832156950225548, 3526803545750650310760216, 146090377422354615989531688, 5948505245302032452585146020, 239776137775416266444362226760

Offset: 19

Author

Alois P. Heinz, Aug 20 2014

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 19..160

Crossrefs

Column k=6 of A242819.

Formula

a(n) ~ c * (3*sqrt(3)/(2*Pi))^n * n! * n^6, where c = 0.000003054026651631929902... = c0 * (c0-1)^6 / (3^6 * 6!), and c0 = (1 + exp(Pi/sqrt(3))) * sqrt(3) / (2*Pi). - Vaclav Kotesovec, Aug 26 2014