login
a(n) = binomial(n+10,10)*6^n.
1

%I #18 Sep 04 2022 04:10:44

%S 1,66,2376,61776,1297296,23351328,373621248,5444195328,73496636928,

%T 930957401088,11171488813056,127964326404096,1407607590445056,

%U 14942295960109056,153692187018264576,1536921870182645760,14984988234280796160,142798123173734645760,1332782482954856693760

%N a(n) = binomial(n+10,10)*6^n.

%C With a different offset, number of n-permutations (n>=10) of 7 objects: r, s, t, u, v, z, x, with repetition allowed, containing exactly 10 u's.

%H Vincenzo Librandi, <a href="/A173124/b173124.txt">Table of n, a(n) for n = 0..400</a>

%H <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (66,-1980,35640,-427680,3592512,-21555072,92378880,-277136640,554273280,-665127936,362797056).

%F From _Chai Wah Wu_, Nov 12 2021: (Start)

%F a(n) = 66*a(n-1) - 1980*a(n-2) + 35640*a(n-3) - 427680*a(n-4) + 3592512*a(n-5) - 21555072*a(n-6) + 92378880*a(n-7) - 277136640*a(n-8) + 554273280*a(n-9) - 665127936*a(n-10) + 362797056*a(n-11) for n > 10.

%F G.f.: -1/(6*x - 1)^11. (End)

%F From _Amiram Eldar_, Sep 04 2022: (Start)

%F Sum_{n>=0} 1/a(n) = 897363955/42 - 117187500*log(6/5).

%F Sum_{n>=0} (-1)^n/a(n) = 2421216420*log(7/6) - 2239392937/6. (End)

%t Table[Binomial[n + 10, 10]*6^n, {n, 0, 20}]

%o (Magma) [6^n* Binomial(n+10, 10): n in [0..20]]; // _Vincenzo Librandi_, Oct 12 2011

%Y Cf. A081136, A081144, A139626, A036084, A050988, A141407, A172501, A173123.

%K nonn,easy

%O 0,2

%A _Zerinvary Lajos_, Feb 10 2010