|
Search: id:A143402
|
|
|
| A143402 |
|
Expansion of x^k/Prod_{t=k..2k}(1-tx) for k=7. |
|
+0
2
|
|
| 0, 0, 0, 0, 0, 0, 0, 1, 84, 3990, 141120, 4138827, 106469748, 2484848080, 53791898160, 1096912870053, 21307466872692, 397605494092170, 7173885616672320, 125794299357058879, 2152559266567924116
(list; graph; listen)
|
|
|
OFFSET
|
0,9
|
|
|
COMMENT
|
a(n) is also the number of forests of 7 labeled rooted trees of height at most 1, with n labels, where any root may contain >= 1 labels.
|
|
LINKS
|
Index entries for sequences related to rooted trees
|
|
FORMULA
|
G.f.: x^7/((1-7x)(1-8x)(1-9x)(1-10x)(1-11x)(1-12x)(1-13x)(1-14x)).
|
|
MAPLE
|
a := proc(k::nonnegint) local M; M := Matrix(k+1, (i, j)-> if (i=j-1) then 1 elif j=1 then [seq(-1* coeff (product (1-t*x, t=k..2*k), x, u), u=1..k+1)][i] else 0 fi); p-> (M^p)[1, k+1] end(7); seq (a(n), n=0..26);
|
|
CROSSREFS
|
7th column of A143395.
Sequence in context: A035737 A035806 A017747 this_sequence A004379 A075906 A075909
Adjacent sequences: A143399 A143400 A143401 this_sequence A143403 A143404 A143405
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Alois P. Heinz (heinz(AT)hs-heilbronn.de), Aug 12 2008
|
|
|
Search completed in 0.003 seconds
|
