OFFSET
1,2
COMMENTS
Column 4 of A220725
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-1) +20*a(n-2) +64*a(n-3) +65*a(n-4) +51*a(n-5) -90*a(n-6) -76*a(n-7) -34*a(n-8) +21*a(n-9) +13*a(n-10) -a(n-11) -a(n-12)
EXAMPLE
Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
.69.47.00.00...00.79.69.47...00.79.79.00...00.00.00.00...00.00.69.47
.36.14.79.00...36.49.13.17...36.34.19.17...00.69.49.00...69.49.37.17
.00.36.46.14...00.00.13.00...00.00.36.14...00.00.16.14...00.13.13.00
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Dec 18 2012
STATUS
approved