A136092 Bisection of A138540.

1, 1, 3, 15, 104, 909, 9449, 112398, 1489410, 21562086, 336086022, 5577242292, 97671172836, 1792348213025, 34268124834495, 679376016769260, 13911118850603610, 293220749128031010

Offset: 0

Author

N. J. A. Sloane, Mar 25 2008

Keywords

• nonn

Links

• Juan B. Gil, Peter R. W. McNamara, Jordan O. Tirrell, Michael D. Weiner, From Dyck paths to standard Young tableaux, arXiv:1708.00513 [math.CO], 2017.

Formula

a(n) = Sum_{j=0..n+1} 180*(2n)!*(2j+2)!*(2n-3j+2)/(j!*(j+1)!*(j+2)!*(j+4)!*(n-j+1)!*(n-j+3)!) (conjectured). - Michael D. Weiner, May 11 2016

36*(n-1)*(2*n-1)*(2*n-3)*a(n-2)-4*(2*n-1)*(5*n^2+22*n+15)*a(n-1)+(n+3)*(n+5)*(n+6)*a(n) = 0 (conjectured). - Michael D. Weiner, May 14 2016