OFFSET
0,2
COMMENTS
A121231(n) >= a(n).
EXAMPLE
The 8 solutions when n=2 are:
00 00 00 01 10 10 10 11
00 01 11 01 00 01 10 00
- from N. J. A. Sloane, Jun 03 2013
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Giovanni Resta, Jun 03 2013
STATUS
approved