OFFSET
1,2
LINKS
Lars Blomberg, Table of n, a(n) for n = 1..1000
G. Bell, A. Lawson, N. Pritchard, and D. Yasaki, Locally infinite Cayley graphs of the integers, arXiv:1711.00809 [math.GT], 2017.
FORMULA
Conjectures from Colin Barker, Dec 28 2017: (Start)
G.f.: x*(1 + x + x^2 - 6*x^3) / ((1 - x)*(1 - 7*x^3)).
a(n) = a(n-1) + 7*a(n-3) - 7*a(n-4) for n>4.
(End)
The second conjecture by Colin Barker is true up to n=1000. - Lars Blomberg, Dec 29 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 28 2017
EXTENSIONS
Terms a(21) and beyond from Lars Blomberg, Dec 29 2017
STATUS
approved