OFFSET
4,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 4..1000
Index entries for linear recurrences with constant coefficients, signature (0,1,5,4,-1,-4,-4).
FORMULA
G.f.: (2*x^3+2*x^2+1)*x^4/((x-1)*(2*x-1)*(x+1)*(x^2+x+1)*(2*x^2+x+1)).
EXAMPLE
a(4) = 1: 1|2|3|4.
a(6) = 3: 14|25|3|6, 14|2|36|5, 1|25|36|4.
a(7) = 7: 14|25|36|7, 14|25|37|6, 14|26|37|5, 15|26|37|4, 15|26|3|47, 15|2|36|47, 1|25|36|47.
a(8) = 7: 14|26|37|58, 14|27|36|58, 15|26|37|48, 15|26|38|47, 15|27|36|48, 16|25|37|48, 16|25|38|47.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Aug 20 2015
STATUS
approved