OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..446
Wikipedia, Lattice path
Wikipedia, Self-avoiding walk
FORMULA
a(n) = Sum_{k=n..n*(n+3)/2} (k+1) * A284414(n,k).
EXAMPLE
a(0) = 1: [(0,0)].
a(1) = 5: [(0,0),(1,0)], [(0,0),(0,1),(1,0)].
a(2) = 21: [(0,0),(1,0),(2,0)], [(0,0),(0,1),(1,0),(2,0)], [(0,0),(1,1),(2,0)], [(0,0),(0,1),(0,2),(1,1),(2,0)], [(0,0),(1,0),(0,1),(0,2),(1,1),(2,0)].
CROSSREFS
KEYWORD
nonn,walk
AUTHOR
Alois P. Heinz, Mar 23 2017
STATUS
approved