0,3

M. D. Atkinson, Permutations which are the union of an increasing and a decreasing subsequence, Electronic Journal of Combinatorics: R6 of Volume 5(1).

f := n->binomial(2*n, n)-sum( 2^(n-m-1)*binomial(2*m, m), m=0.. n-1 );

Sequence in context: A116710 A116707 A116704 this_sequence A107243 A107244 A107246

Adjacent sequences: A029756 A029757 A029758 this_sequence A029760 A029761 A029762

nonn

njas