A145546 Number of distinct values taken by 6^6^...^6 (with n 6's and parentheses inserted in all possible ways).

1, 1, 2, 4, 9, 20, 48, 115, 286, 718, 1838, 4750, 12431, 32790, 87225, 233534, 629123, 1703586, 4635181, 12664335, 34734322, 95592704, 263909594

Offset

1,3

Links

Table of n, a(n) for n=1..23.

R. K. Guy and J. L. Selfridge, The nesting and roosting habits of the laddered parenthesis, Amer. Math. Monthly 80 (8) (1973), 868-876.

Index entries for sequences related to parenthesizing

Crossrefs

Cf. A002845, A003018, A003019, A145545, A145547, A145548, A145549, A145550, A000081.

Sequence in context: A255638 A215971 A034825 * A292553 A318802 A318855

Adjacent sequences: A145543 A145544 A145545 * A145547 A145548 A145549

Keyword

more,nonn

Author

Jon E. Schoenfield, Oct 13 2008

Status

approved