A246323 Triangle read by rows: T(n,k) = number of normal planar lambda terms of size n with k free variables (n >= 1, 1 <= k <= n).

1, 2, 1, 9, 6, 2, 54, 40, 20, 5, 378, 295, 175, 70, 14, 2916, 2346, 1526, 756, 252, 42, 24057, 19739, 13587, 7602, 3234, 924, 132, 208494, 173426, 123978, 74964, 36828, 13728, 3432, 429

Offset: 1

Author

N. J. A. Sloane, Aug 28 2014

Keywords

• nonn
• tabl

Examples

			Triangle begins:
1
2,1
9,6,2
54,40,20,5
378,295,175,70,14
2916,2346,1526,756,252,42
24057,19739,13587,7602,3234,924,132,
208494,173426,123978,74964,36828,13728,3432,429
...
		

Links

• Noam Zeilberger, Alain Giorgetti, A correspondence between rooted planar maps and normal planar lambda terms, arXiv:1408.5028 [cs.LO], 2014.

Crossrefs

Cf. A000108, A000984, A000168, A246322.