1,2

F. Faase, Counting Hamilton cycles in product graphs

n>1, a(n)=ceiling((1-sqrt(1/3))*(2+sqrt(3))^n); recurrence: a(1)=1, a(2)=6, a(3)=22, and for n>3 a(n)=4*a(n-1)-a(n-2) - Benoit Cloitre (benoit7848c(AT)orange.fr), Mar 28 2003

O.g.f.: -x*(-1-2*x+x^2)/(1-4*x+x^2) = -x-2+(-6*x+2)/(1-4*x+x^2) . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 23 2007

First differences of A052530 and A071954.

Equals 2 * A001835(n), n>1.

Adjacent sequences: A003696 A003697 A003698 this_sequence A003700 A003701 A003702

Sequence in context: A032195 A111566 A051945 this_sequence A047124 A046365 A078418

nonn

Frans Faase (Frans_LiXia(AT)wxs.nl)