OFFSET
1,1
COMMENTS
Paths are self-avoiding from one corner to the diagonally opposite corner.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..200
FORMULA
Conjectured g.f.: x*(1 - x)*(3 - 29*x + 51*x^2 + 595*x^3 - 3879*x^4 + 9553*x^5 - 8366*x^6 - 8026*x^7 + 22931*x^8 - 13117*x^9 - 5593*x^10 + 7955*x^11 - 6118*x^12 + 6842*x^13 + 1884*x^14 - 6824*x^15 + 519*x^16 + 1991*x^17 - 206*x^18 - 230*x^19 + 13*x^20 + 9*x^21)/((1 - 8*x + 15*x^2 - 5*x^3 - 9*x^4 + 2*x^5 + x^6)^2*(1 - 4*x + 7*x^2 - 3*x^3 - 7*x^4 + 2*x^5 + x^6)^2). - Andrew Howroyd, Jan 06 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
David Scambler, Oct 17 2010
EXTENSIONS
a(10)-a(13) from Alois P. Heinz, Dec 10 2011
Terms a(14) and beyond from Andrew Howroyd, Jan 06 2020
STATUS
approved