A098091 Graded dimension of the space of invariant bilinear forms on the free pre-Lie algebra on one generator.

1, 1, 4, 7, 17, 36, 88, 196, 481, 1148, 2838, 7020, 17708, 44837, 114971, 296457

Offset: 5

Author

F. Chapoton, Sep 14 2004

Keywords

• nonn
• more

Comments

The sequence starts at index 5 because the previous terms vanish.

Crossrefs

This is related in some sense to A000081.

Cf. A051573, A123256.

Formula

It seems that a(n+1) = A000081(n) - A051573(n). - Andrey Zabolotskiy, Aug 05 2024