|
Search: id:A131631
|
|
|
| A131631 |
|
Supersubfactorials: partial product of positive subfactorials (A000166). |
|
+0
1
|
|
| 1, 2, 18, 792, 209880, 389117520, 5771780174160, 770509566129663360, 1028600220910021528728960, 15104551945968674840127424147200, 2661646219535110627933754465838408595200
(list; graph; listen)
|
|
|
OFFSET
|
2,2
|
|
|
COMMENT
|
This is to subfactorials (A000166, rencontres numbers, or derangements) as superfactorials (A000178) are to factorials (A000142).
|
|
FORMULA
|
a(n) = PRODUCT[k = 2 to n] A000166(k).
|
|
EXAMPLE
|
a(2) = 1.
a(3) = 1 * 2 = 2.
a(4) = 1 * 2 * 9 = 18 = 2 * 3^2.
a(5) = 1 * 2 * 9 * 44 = 792 = 2^3 * 3^2 * 11.
a(6) = 1 * 2 * 9 * 44 * 265 = 209880 = 2^3 * 3^2 * 5 * 11 * 53.
a(7) = 1 * 2 * 9 * 44 * 265 * 1854 = 389117520 = 2^4 * 3^4 * 5 * 11 * 53 * 103.
|
|
CROSSREFS
|
Cf. A000142, A000166, A000178.
Sequence in context: A071352 A013035 A132520 this_sequence A015190 A013040 A139111
Adjacent sequences: A131628 A131629 A131630 this_sequence A131632 A131633 A131634
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Jonathan Vos Post (jvospost3(AT)gmail.com), Sep 01 2007
|
|
|
Search completed in 0.002 seconds
|
