OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 35*n^2 + n + 1 for n>1.
Conjectures from Colin Barker, Sep 10 2018: (Start)
G.f.: x*(31 + 50*x - 17*x^2 + 6*x^3) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>4.
(End)
EXAMPLE
Some solutions for n=4:
..0...-6...-2...-9...-4...-3...-7...-3....9....8...-1....5...-3....8..-13...-2
.-2...-2....8....7...-4...-9...13....2....2..-10....8....3...-5...-6....3....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 19 2013
STATUS
approved