OFFSET
1,3
LINKS
R. J. Mathar, Comments on this sequence
Eric Weisstein's World of Mathematics, Complete Graph.
Eric Weisstein's World of Mathematics, Euler Path.
Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1).
FORMULA
a(1)=0; a(2n+1) = n*(n-1)/2-1 = A014107(n+1), n>0; a(2n)=n*(n-2)/2+1= A001844(n-1). - Martin Fuller, R. J. Mathar and Mitch Harris, Dec 06 2007
O.g.f.: x^2*(x^4-2*x^3-x^2-x-1)/((-1+x)^3 *(x+1)^2) . - R. J. Mathar, Jan 17 2008
EXAMPLE
a(4) = 5 because the length of the longest path between any two distinct vertices in K_4 is 5.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Ryan Propper, Jun 18 2005
STATUS
approved