OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Hamiltonian Cycle
Eric Weisstein's World of Mathematics, Moebius Ladder
Index entries for linear recurrences with constant coefficients, signature (1,1,-1).
FORMULA
a(n odd) = 2*n, a(n even) = 2*n+4.
a(n) = 2(n+1)+2(-1)^n. - Paul Barry, Feb 17 2008
a(n) -a(n-4) = 8. - Paul Curtz, Apr 19 2011
a(n) = +1*a(n-1) +1*a(n-2) -1*a(n-3). - Joerg Arndt, Apr 22 2011
G.f.: 2*x*(1+3*x-2*x^2)/((1-x)^2*(1+x)). - Colin Barker, Jan 23 2012
a(n) = 2*A014681(n+1). - R. J. Mathar, Nov 27 2015
PROG
(Magma) [2*(n+1)+2*(-1)^n: n in [1..70]]; // Vincenzo Librandi, Aug 11 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Nov 05 2006
STATUS
approved