-1688

Appears in sequences

• Expansion of e.g.f. sin(x/cosh(x)) (odd powers only).at n=3A009563
• Triangle read by rows: T(n,k) is the k-th generalized Eulerian number of order n and degree 4, n >= 1.at n=29A211234
• Let b(0)=n, b(1)=n+1, b(2)=n+2, and b(k)=(b(k-3)*b(k-2)*b(k-3)) mod (b(k-3)+b(k-2)+b(k-1)) for k>=3. Continue until either b(k)=0, in which case a(n)=k, or the ordered triple [b(k-2),b(k-1),b(k)] has appeared before, in which case a(n)=-k. If neither of these ever occur, then a(n)=0.at n=37A309869