|
| |
|
|
A109901
|
|
a(n) = n^2 choose n*(n+1)/2.
|
|
0
| |
|
|
1, 1, 4, 84, 8008, 3268760, 5567902560, 39049918716424, 1118770292985239888, 130276394656770614583240, 61448471214136179596720592960, 117118180539414377821494470432491764
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,3
|
|
|
FORMULA
| a(n) = C(n^2, n*(n+1)/2) = (n^2!)/((n(n+1)/2)!*(n(n-1)/2)!).
a(n) = C(n^2, n*(n-1)/2).
|
|
|
EXAMPLE
| a(6) = 36!/(21!*15!) =5567902560.
|
|
|
MAPLE
| seq(binomial(n^2, n*(n+1)/2), n=0..12); (Emeric Deutsch)
|
|
|
MATHEMATICA
| Table[Binomial[n^2, (n(n+1))/2], {n, 20}] (* From Harvey P. Dale, June 04 2011 *)
|
|
|
PROG
| (PARI) a(n)=binomial(n^2, n*(n+1)/2)
|
|
|
CROSSREFS
| Cf. variants: A014062 (C(n^2,n*(n-1)), A135757 (C(n*(n+1),n*(n+1)/2)).
Sequence in context: A012189 A012076 A173211 * A015018 A204245 A184100
Adjacent sequences: A109898 A109899 A109900 * A109902 A109903 A109904
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jul 14 2005
|
|
|
EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jul 16 2005
Offset changed to 0 (with a(0)=1), and name changed slightly by Paul D. Hanna, Jun 24 2011.
|
| |
|
|
