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

1,4

Links

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

Example

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

Crossrefs

Cf. A140518, A007764.

Sequence in context: A226931 A013341 A077795 * A175596 A261397 A238906

Adjacent sequences: A038493 A038494 A038495 * A038497 A038498 A038499

Keyword

nonn,walk

Author

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

Extensions

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

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

Status

approved