68067

Appears in sequences

• a(n) = 6*a(n-1) + 3*a(n-2) for n > 2, a(0)=1, a(1)=6.at n=6A090018
• Sum of the lengths of the first ascents in all n-length left factors of Dyck paths.at n=16A191782
• Square array T(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of g.f. 1/(1 - 2*k*x - k*x^2).at n=51A342134