OFFSET
0,2
COMMENTS
Number of n-permutations (n>=6) of 10 objects p, r, q, u, v, w, z, x, y, z with repetition allowed, containing exactly six (6) u's.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..400
Index entries for linear recurrences with constant coefficients, signature (63,-1701,25515,-229635,1240029,-3720087,4782969).
FORMULA
a(n) = C(n + 6, 6)*9^n.
From Amiram Eldar, Aug 29 2022: (Start)
Sum_{n>=0} 1/a(n) = 1042074/5 - 1769472*log(9/8).
Sum_{n>=0} (-1)^n/a(n) = 5400000*log(10/9) - 2844729/5. (End)
MAPLE
MATHEMATICA
Table[Binomial[n + 6, 6]*9^n, {n, 0, 20}]
PROG
(Magma) [Binomial(n+6, 6)*9^n: n in [0..20]]; // Vincenzo Librandi, Oct 13 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Zerinvary Lajos, Feb 12 2010
STATUS
approved