A145545 Number of distinct values taken by 5^5^...^5 (with n 5's and parentheses inserted in all possible ways).

1, 1, 2, 4, 9, 20, 48, 115, 285, 715, 1826, 4711, 12303, 32387, 85964, 229662, 617300, 1667787, 4527290, 12340688, 33766612, 92707834, 255329106

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.

MathOverflow, MathOverflow discussion of related questions

Index entries for sequences related to parenthesizing

Crossrefs

Cf. A002845, A003018, A003019, A145546, A145547, A145548, A145549, A145550, A000081.

Sequence in context: A255637 A215796 A034824 * A182378 A318801 A318854

Adjacent sequences: A145542 A145543 A145544 * A145546 A145547 A145548

Keyword

more,nonn

Author

Jon E. Schoenfield, Oct 13 2008

Status

approved