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A194720 Number of n-ary words beginning with the first character of the alphabet, that can be built by inserting eight doublets into the initially empty word. 2

%I #9 Jul 13 2015 19:08:45

%S 0,1,6435,381333,5068915,33563481,148733571,507709165,1443039123,

%T 3581326065,8006545891,16475259141,31690921395,57644499913,

%U 100028603715,166732334301,268424064211,419229350625,637511191203,946759829365,1376599316211,1963918036281

%N Number of n-ary words beginning with the first character of the alphabet, that can be built by inserting eight doublets into the initially empty word.

%H Alois P. Heinz, <a href="/A194720/b194720.txt">Table of n, a(n) for n = 0..1000</a>

%F G.f.: x * (1 +6427*x +329881*x^2 +2198375*x^3 +3329195*x^4 +1251089*x^5 +91803*x^6 +429*x^7) / (x-1)^8.

%F a(0) = 0, a(n) = 1 +(14 +(90 +(350 +(910 +(1638 +(2002 +1430 * (n-1)) * (n-1)) * (n-1)) * (n-1)) * (n-1)) * (n-1)) * (n-1) for n>0.

%e a(1) = 1: a^16 (with 1-ary alphabet {a}).

%p a:= n-> `if`(n=0, 0, (x-> 1+(14+(90+(350+(910+(1638+(2002+1430*x)*

%p x)*x)*x)*x)*x)*x)(n-1)):

%p seq(a(n), n=0..30);

%Y Row n=8 of A183134.

%K nonn

%O 0,3

%A _Alois P. Heinz_, Sep 02 2011

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)