OFFSET
1,5
COMMENTS
If we define b(n) by b(n)=local(nr,fn,cn); nr=0; fn=floor(n/2); cn=ceiling(n/2); forstep (i=n,4,-2,nr=nr+(i-2)*fn+(i-4)*cn); nr then a(n) is given by (A007678(2n)-b(2n))/(2n).
This b(n) is given by (n-2)*(2*n^2 - 4*n + 3*(-1)^n - 3)/8 for n > 1. - R. J. Mathar, Oct 18 2013
FORMULA
a(n) = A007678(2*n)/(2*n) - (n-1)^2. - M. F. Hasler, Aug 06 2021
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Jon Perry, Jul 08 2003
EXTENSIONS
The last term seemed to be corrupted and has now been deleted. - N. J. A. Sloane, Oct 29 2006
Edited and more terms from M. F. Hasler, Aug 06 2021
STATUS
approved