757016domain: NAppears in sequencesa(n) = (4/3)*u*(u^3+6*u^2+8*u-3) where u=floor((3*n+5)/2).at n=15A160451a(1) = 0, a(2) = 4, a(n) = a(n-1) + a(n-2) - 1.at n=28A187890