73120

Appears in sequences

• Expansion of (1-x)/(1-2*x-2*x^3).at n=14A077999
• Expansion of (1 + x)/(1 + 2*x + 2*x^3).at n=14A110524
• a(1) = a(2) = a(3) = 1; for n>3, a(n) = a(n-1) + a(n-2) + a(n-3) iff n-1 is prime, otherwise a(n) = a(n-1) + 1.at n=38A113057
• G.f.: A(x,y,z) = Sum_{n>=0} ((2n)!/n!^2)*[Sum_{k=0..2n} T(n,k)*z^k]*x^(2n)*y^n/(1-x-xy)^(4n+1) where A(x,y,x+xy) = Sum_{n>=0, k=0..n} C(n,k)^4*x^n*y^k at z = x+xy; this is the triangle of coefficients T(n,k), read by rows.at n=20A187056
• Principal diagonal of the convolution array A213847.at n=23A213848
• Triangle of generalized Eulerian numbers T(n,k) = <n,k>_2 read by rows, n >= 1, 0 <= k < 2*n.at n=30A269742
• Number of nonnegative integer n X n matrices with row and column sums 2 and sum of entries below the main diagonal n - 1.at n=5A332729