A119831 - OEIS

%I #4 Jan 19 2013 11:14:08

%S 1,6,1,720,120,1,362880,60480,504,1,479001600,79833600,665280,1320,1,

%T 1307674368000,217945728000,1816214400,3603600,2730,1,

%U 6402373705728000,1067062284288000,8892185702400,17643225600,13366080,4896,1

%N Number triangle (3n)!/(3k)!.

%C Row sums are A087350. Inverse is bi-diagonal array A119832.

%F Number triangle T(n,k)=[k<=n]*(3n)!/(3k)!

%e Triangle begins

%e 1,

%e 6, 1,

%e 720, 120, 1,

%e 362880, 60480, 504, 1,

%e 479001600, 79833600, 665280, 1320, 1,

%e 1307674368000, 217945728000, 1816214400, 3603600, 2730, 1

%t Flatten[Table[(3n)!/(3k)!,{n,0,10},{k,0,n}]] (* _Harvey P. Dale_, Jan 19 2013 *)

%Y Cf. A119828.

%K easy,nonn,tabl

%O 0,2

%A _Paul Barry_, May 25 2006