OFFSET
1,1
COMMENTS
Column 4 of A220621
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 16*a(n-1) -18*a(n-2) -114*a(n-3) +230*a(n-4) -66*a(n-5) -78*a(n-6) +48*a(n-7) -4*a(n-8) -4*a(n-9) +a(n-10)
EXAMPLE
Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
..0..9..6..4....0..0..6..4....0..6..4..0....9..7..0..0....9..7..0..0
..0..7..1..0....0..0..0..0....0..0..0..7....3..1..6..4....3..1..6..4
..3..0..0..0....0..0..6..4....0..0..3..0....0..0..0..0....0..6..4..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Dec 17 2012
STATUS
approved