OFFSET
1,2
COMMENTS
We use unit moves parallel to the triangle edges.
LINKS
Rémy Sigrist, Python program for A343307
Eric Weisstein's World of Mathematics, Triangular Grid Graph
EXAMPLE
For n = 3:
- we have the following paths:
. .
.
. . .
.
. o---o---o
.
.
. . . .
.
. o . o o . o
. / \ / \ / \ / \
. o o---o o o o o---o o
.
.
. . . .
.
. o---o o---o o---o
. / / / \ \ \
. o o---o o . o o---o o
.
.
. o o o
. / \ / \ / \
. o o o o o o
. / / / \ \ \
. o o---o o . o o---o o
- so a(3) = 10.
PROG
(Python) # See Links section.
CROSSREFS
KEYWORD
nonn,walk,hard
AUTHOR
Rémy Sigrist, Apr 11 2021
EXTENSIONS
a(14)-a(15) from Andrew Howroyd, Feb 04 2022
STATUS
approved