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

1,2

Links

Table of n, a(n) for n=1..36.

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

Example

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
...

Crossrefs

Cf. A000108, A000984, A000168, A246322.

Sequence in context: A235595 A061356 A141028 * A201685 A120671 A245461

Adjacent sequences: A246320 A246321 A246322 * A246324 A246325 A246326

Keyword

nonn,tabl

Author

N. J. A. Sloane, Aug 28 2014

Status

approved