OFFSET
1,1
COMMENTS
Row 3 of A181236.
LINKS
Robert Israel, Table of n, a(n) for n = 1..630 (first 112 terms from R. H. Hardin)
FORMULA
From Robert Israel, Oct 30 2014: (Start)
a(n) = 2 * (1 + (3*n)!/(n!)^3).
a(n+1) = (3*(3*n+2)*(3*n+1)*a(n) - 52*n^2 - 50*n - 10)/(n+1)^2. (End)
EXAMPLE
All solutions for 3 X 3:
..0..0..0....0..0..1....0..0..1....0..1..0....0..1..0....0..1..1....0..1..1
..0..0..0....0..1..0....1..0..0....0..0..1....1..0..0....1..0..1....1..1..0
..0..0..0....1..0..0....0..1..0....1..0..0....0..0..1....1..1..0....1..0..1
...
..1..0..0....1..0..0....1..0..1....1..0..1....1..1..0....1..1..0....1..1..1
..0..0..1....0..1..0....0..1..1....1..1..0....0..1..1....1..0..1....1..1..1
..0..1..0....0..0..1....1..1..0....0..1..1....1..0..1....0..1..1....1..1..1
MAPLE
seq(2 * (1 + (3*n)!/(n!)^3), n = 1 .. 20); # Robert Israel, Oct 30 2014
MATHEMATICA
Table[2 (1 + (3 n)! / (n!)^3), {n, 20}] (* Vincenzo Librandi, Oct 30 2014 *)
PROG
(Magma) [2*(1+Factorial(3*n)/Factorial(n)^3): n in [1..20]]; // Vincenzo Librandi, Oct 30 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 10 2010
STATUS
approved