-20790

Appears in sequences

• Triangle T(n,k), n >= 0, 0 <= k <= n, read by rows. Let A(n,k) be the triangle in A097474. Then T(n,k) is defined by the orthogonality relations Sum_{j=i..r} T(r,j)*A(j,i)*2^-floor((j+3)/2) = 0 if i != r, = (2r+1)!/(r!*2^r) if i = r.at n=18A097749
• a(2n) = -A106328(n), a(2n+1) = A054488(n).at n=12A108931
• a(1) = 1, a(2) = -1, a(3) = 2; for n > 3, a(n) = -(2*n-5)*a(n-1).at n=7A129779
• Triangle read by rows: Riordan array (1/(1-9x)^(2/3), x/(9x-1)).at n=16A283151