65221

Appears in sequences

• a(0) = 1, a(1) = 2; for n>0, a(2*n) = 3*a(2*n-1) - a(2*n-2), a(2*n+1) = 3*a(2*n) - a(2*n-1) - a(n-1).at n=12A129804
• Triangle read by rows: row n gives coefficients of expansion of q-reduced tangent number d_{n}(q) in powers of q.at n=45A143195
• Number of forests of trees on n or fewer nodes using a subset of labels 1..n, also row sums of triangle A144258.at n=7A144259