90880

Appears in sequences

• a(n)=n for n <= 3, a(n) = 2a(n-1) - 2a(n-2) + 2a(n-3) for n >= 4.at n=27A104767
• Coefficient of x in the reduction (by x^2->x+1) of polynomial p(n,x) identified in Comments.at n=9A192351
• T(n, m) = Sum_{k=1..(m+3)/2} C(m-k+2, k-1)*C(n+1, k-1)*C(n-m+k-1, k-1)*C(2*n-2*k+4, 2*m-4*k+5)/(C(2*k-2, k-1)*C(2*m-2*k+4, 2*k-2))/2, triangle read by rows.at n=51A338372