|
| |
|
|
A140802
|
|
Binomial(n+3,3)*8^n.
|
|
7
| |
|
|
1, 32, 640, 10240, 143360, 1835008, 22020096, 251658240, 2768240640, 29527900160, 307090161664, 3126736191488, 31267361914880, 307863255777280, 2990671627550720, 28710447624486912, 272749252432625664, 2567051787601182720, 23959150017611038720
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,2
|
|
|
COMMENTS
| With a different offset, number of n-permutations (n>=3) of 9 objects: r, s, t, u, v, w, z, x, y with repetition allowed, containing exactly (3) three u's.
Example:
(n=4) a(1)=32
uuur, uuru, uruu, ruuu,
uuus, uusu, usuu, suuu,
uuut, uutu, utuu, tuuu,
uuuv, uuvu, uvuu, vuuu,
uuuw, uuwu, uwuu, wuuu,
uuuz, uuzu, uzuu, zuuu,
uuux, uuxu, uxuu, xuuu,
uuuy, uuyu, uyuu, yuuu
|
|
|
LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..400
|
|
|
FORMULA
| G.f.: 1/(1-8*x)^4. - Vincenzo Librandi, Oct 16 2011
|
|
|
MAPLE
| seq(binomial(n+3, 3)*8^n, n=0..19);
|
|
|
PROG
| (Other) SAGE:[lucas_number2(n, 8, 0)*binomial(n, 3)/8^3 for n in xrange(3, 20)] # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 13 2009]
(MAGMA) [8^n* Binomial(n+3, 3): n in [0..20]]; // Vincenzo Librandi, Oct 16 2011
|
|
|
CROSSREFS
| Sequence in context: A013699 A004337 A181240 * A028204 A028190 A028202
Adjacent sequences: A140799 A140800 A140801 * A140803 A140804 A140805
|
|
|
KEYWORD
| nonn,easy
|
|
|
AUTHOR
| Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jul 15 2008
|
| |
|
|
