OFFSET
1,1
FORMULA
a(n) = 2^ceiling(n(n+1)/6). - Giovanni Resta, Aug 23 2017
EXAMPLE
All solutions for n = 3:
0 0 1 1
0 0 1 1 0 0 1 1
0 0 0 0 1 0 1 0 1 1 1 1
MATHEMATICA
Table[2^Ceiling[n (n + 1)/6], {n, 20}] (* Giovanni Resta, Aug 23 2017 *)
PROG
(PARI) a(n) = 2^ceil(n*(n+1)/6) \\ after Giovanni Resta's formula
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Felix Fröhlich, Aug 22 2017
EXTENSIONS
More terms from Giovanni Resta, Aug 23 2017
STATUS
approved