0,2

If X_1, X_2, ..., X_n is a partition of the set {1,2,...,2*n} into blocks of size 2 then, for n>=1, a(n) is equal to the number of functions f : {1,2,..., 2*n}->{1,2,3,4,5,6} such that for fixed y_1,y_2,...,y_n in {1,2,3,4,5,6} we have f(X_i)<>{y_i}, (i=1,2,...,n). - Milan R. Janjic (agnus(AT)blic.net), May 24 2007

Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets

Tanya Khovanova, Recursive Sequences

G.f.: 1/(1-35*x). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 24 2008]

Sequence in context: A029546 A126158 A095153 this_sequence A158733 A029560 A135923

Adjacent sequences: A009976 A009977 A009978 this_sequence A009980 A009981 A009982

nonn

N. J. A. Sloane (njas(AT)research.att.com).