657468

Appears in sequences

• Let K be a local ring with a principal maximal ideal J of nilpotent degree 4 with |K/J|>2; a(n) = number of D-invariant ideals in the ring R_n(K,J).at n=7A221704
• G.f. satisfies A(x) = 1 + 2*x + x^3*A(x)^3.at n=18A367073