A276032 Number of refinements of the partition n^1 with all numbers taken modulo 2.

1, 2, 3, 7, 8, 21, 22, 63, 64, 195, 196, 624, 625, 2054, 2055, 6916, 6917, 23712, 23713, 82498, 82499, 290510, 290511, 1033410, 1033411, 3707850, 3707851, 13402695, 13402696, 48760365, 48760366, 178405155, 178405156, 656043855, 656043856, 2423307045

Offset

1,2

Comments

Consider the ranked poset L(n) of partitions defined in A002846, and take the elements of each node modulo 2, collapsing two equivalent nodes into 1. Then a(n) is the total number of paths of all lengths 0,1,...,n-1 that start at (n mod 2)^1 and end at any node in the poset.

Odd-indexed terms are the partial sums of Catalan numbers: A014138.

Even-indexed terms are one less than the following odd-indexed term.

Links

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

Caleb Ji, Enumerative Properties of Posets Corresponding to a Certain Class of Games of No Strategy, Journal of Integer Sequences, Vol. 20 (2017), Article 17.5.1.

Crossrefs

Cf. A276033, A014138.

Sequence in context: A181658 A251541 A325105 * A114281 A137823 A024540

Adjacent sequences: A276029 A276030 A276031 * A276033 A276034 A276035

Keyword

nonn

Author

Caleb Ji, Aug 17 2016

Status

approved