|
|
A056923
|
|
Write the integers in groups: 0; 1,2; 3,4,5; 6,7,8,9; ... and form the product of the members of each group.
|
|
2
|
|
|
0, 2, 60, 3024, 240240, 27907200, 4475671200, 948964262400, 257256702743040, 86839771951296000, 35728290125079552000, 17602963463032472448000, 10233395250958706770944000, 6932022668773077815267328000
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
COMMENTS
|
Each group begins with a triangular number and proceeds until one short of the next triangular number.
Also, the number under the radical using Brahmagupta's formula for an n-sided cyclic quadrilateral with sides 1..n. - Ben Paul Thurston, Dec 05 2006
|
|
LINKS
|
|
|
FORMULA
|
a(n) = (n (n + 3)/2)!/((n - 1)(n + 2)/2)!.
|
|
MAPLE
|
a:= n-> mul(n*(n+1)/2+j, j=0..n):
|
|
MATHEMATICA
|
Table[(n (n + 3)/2)!/((n - 1)(n + 2)/2)!, {n, 0, 15}]
Times@@Range[First[#], Last[#]-1]&/@Partition[Accumulate[Range[0, 15]], 2, 1] (* Harvey P. Dale, Apr 25 2014 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|