A038496 Number of self-avoiding paths with diagonal steps from corner to opposite corner of n X n grid.

1, 1, 1, 3, 9, 53, 465, 9815, 288601, 19609857, 1719287011, 340800846539, 88312098753293, 52527897517470365, 41335202747219808853, 74965326513925821171199, 179806473914469748125175893, 992651698460472155144461591193

Offset: 1

Author

David W. Wilson, based on a suggestion of Felice Russo

Keywords

• nonn
• walk

Examples

			Illustration of a(4)=3:
.  o   o         o   o         o   o
.   \             \ / \         \
.    o   o         o   o         o   o
.     \               /         /
.  o   o         o   o         o   o
.       \             \         \ / \
.    o   o         o   o         o   o
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..25

Crossrefs

Cf. A140518, A007764.

Extensions

a(11)-a(12) from R. H. Hardin, Jul 31 2008

a(13)-a(18) from Andrew Howroyd, Apr 07 2016