A111554 Column 1 of triangle A111553.

1, 2, 10, 72, 632, 6352, 70912, 864192, 11371072, 160333952, 2409420032, 38428442112, 648333665792, 11538313372672, 216092576714752, 4249731095212032, 87591291183296512, 1888669450881032192

Offset

0,2

Comments

a(n) is the number of increasing strict binary trees with 2n-1 nodes that avoid 132. For more information about increasing strict binary trees with an associated permutation, see A245894. - Manda Riehl, Aug 07 2014

Links

Table of n, a(n) for n=0..17.

Prog

(PARI) {a(n)=if(n<0, 0, (matrix(n+2, n+2, m, j, if(m==j, 1, if(m==j+1, -m+1, -(m-j-1)*polcoeff(log(sum(i=0, m, (i+3)!/3!*x^i)), m-j-1))))^-1)[n+2, 2])}

Crossrefs

Cf. A111553.

Sequence in context: A271214 A366241 A321446 * A177384 A354288 A182525

Adjacent sequences: A111551 A111552 A111553 * A111555 A111556 A111557

Keyword

nonn

Author

Paul D. Hanna, Aug 07 2005

Status

approved