OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..121
FORMULA
Empirical: a(n) = 9*a(n-1) - 20*a(n-2) for n>8.
Conjectures from Colin Barker, Sep 10 2018: (Start)
G.f.: x*(33 + 268*x + 1994*x^2 + 6844*x^3 - 35854*x^4 - 86008*x^5 - 163840*x^6 - 57600*x^7) / ((1 - 4*x)*(1 - 5*x)).
a(n) = 5^(3+n) - 4^(3+n) for n>6.
(End)
EXAMPLE
Some solutions for n=4:
.12..-10....2...-7....8...-5....2..-13...-7..-15...-6...-3....5....3....7....2
.-7....8....3....6...-2....1....0...13....4....9....0....4...-2...-3..-12....3
.-1...-6....1....1...-1...-3...-7..-12....1....0....9...-1...-6....2...12...-1
..4....8...-7...-1...-4...-2...10...12...-6...-2..-13...-3...10...-5...-6....5
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 19 2013
STATUS
approved