|
Search: id:A054851
|
|
|
| A054851 |
|
2^(n-7)*C(n,7). Number of 7D hypercubes in an n-dimensional hypercube. |
|
+0
11
|
|
| 1, 16, 144, 960, 5280, 25344, 109824, 439296, 1647360, 5857280, 19914752, 65175552, 206389248, 635043840, 1905131520, 5588385792, 16066609152, 45364543488, 126012620800, 344876646400, 931166945280, 2483111854080
(list; graph; listen)
|
|
|
OFFSET
|
7,2
|
|
|
COMMENT
|
If X_1,X_2,...,X_n is a partition of a 2n-set X into 2-blocks then, for n>6, a(n) is equal to the number of (n+7)-subsets of X intersecting each X_i (i=1,2,...,n). - Milan R. Janjic (agnus(AT)blic.net), Jul 21 2007
With a different offset, number of n-permutations (n>=7) of 3 objects: u,v,z with repetition allowed, containing exactly seven (7) u's. Example: a(1)=16 because we have uuuuuuuv, uuuuuuvu, uuuuuvuu, uuuuvuuu, uuuvuuuu, uuvuuuuu, uvuuuuuu, vuuuuuuu, uuuuuuuz, uuuuuuzu, uuuuuzuu, uuuuzuuu, uuuzuuuu, uuzuuuuu, uzuuuuuu, and zuuuuuuu. - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 23 2008
|
|
LINKS
|
Milan Janjic, Two Enumerative Functions
|
|
FORMULA
|
a(n)=2*a(n-1)+A002409(n-1)
|
|
MAPLE
|
seq(binomial(n+7, 7)*2^n, n=0..21); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 23 2008
|
|
CROSSREFS
|
Cf. A000079, A001787, A001788, A001789, A003472, A054849, A002409, A038207.
a(n+8) = A082141(n+1)/2.
Sequence in context: A060300 A128985 A004409 this_sequence A000762 A086952 A077485
Adjacent sequences: A054848 A054849 A054850 this_sequence A054852 A054853 A054854
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Henry Bottomley (se16(AT)btinternet.com), Apr 14 2000
|
|
EXTENSIONS
|
More terms from James A. Sellers (sellersj(AT)math.psu.edu), Apr 15 2000
|
|
|
Search completed in 0.002 seconds
|
