A134635 - OEIS

A134635

Row sums of triangle A134634.

1, 2, 6, 18, 54, 164, 508, 1610, 5222, 17308, 58484, 200948, 700348, 2470472, 8804024, 31648858, 114623366, 417820972, 1531629764, 5642508508, 20878731476, 77561756152, 289156105544, 1081466311108, 4056621689564, 15257327887384, 57525469116168, 217383333920040, 823195469508792, 3123379468819600, 11872247508521072, 45203794091311354

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..31.

Noah Arbesfeld, Partial permutations avoiding pairs of patterns, Discrete Math., 313 (2013), 2614-2625.

FORMULA

Conjecture: (n+1)*a(n) +(-7*n+1)*a(n-1) +2*(7*n-8)*a(n-2) +4*(-2*n+5)*a(n-3)=0. - R. J. Mathar, May 30 2014

a(n) = 2*A000108(n) - A126966(n). - Mélika Tebni, Feb 11 2024

EXAMPLE

a(3) = 18 = sum of row 3 terms of triangle A134634: (5 + 4 + 4 + 5).

MAPLE