OFFSET
0,5
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..200 (terms n = 1..196 from R. H. Hardin)
EXAMPLE
All solutions for n=4
.-1..1...-1.-1....1..1
.-1..1....1..1...-1.-1
.-1..1....1..1...-1.-1
.-1..1...-1.-1....1..1
MAPLE
b:= proc(x, y, t) option remember; `if`(x=0, 1, add(`if`(abs(j)
<x and abs(y)<x*(x+1)/2, b(x-1, y+j, j), 0), j=t-1..t+1))
end:
a:= n-> b(n, 0$2):
seq(a(n), n=0..33); # Alois P. Heinz, Mar 25 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 05 2013
EXTENSIONS
a(0)=1 prepended by Alois P. Heinz, Mar 25 2020
STATUS
approved