cp's OEIS Frontend

A194719 Number of n-ary words beginning with the first character of the alphabet, that can be built by inserting seven doublets into the initially empty word.

%I A194719 #9 Jul 13 2015 19:08:13
%S A194719 0,1,1716,54573,492724,2467137,8786436,25066621,61189668,133071009,
%T A194719 264735892,490704621,858686676,1432583713,2295801444,3554870397,
%U A194719 5343375556,7826194881,11204046708,15718346029,21656369652,29356730241,39215159236,51690598653,67311601764
%N A194719 Number of n-ary words beginning with the first character of the alphabet, that can be built by inserting seven doublets into the initially empty word.
%H A194719 Alois P. Heinz, <a href="/A194719/b194719.txt">Table of n, a(n) for n = 0..1000</a>
%F A194719 G.f.: -x*(1+1709*x+42582*x^2+146714*x^3+104077*x^4+13665*x^5+132*x^6) / (x-1)^7.
%F A194719 a(0) = 0, a(n) = 1+(12+(65+(208+(429+(572+429*(n-1)) * (n-1)) * (n-1)) * (n-1)) * (n-1)) * (n-1) for n>0.
%e A194719 a(1) = 1: a^14 (with 1-ary alphabet {a}).
%p A194719 a:= n-> `if`(n=0, 0, (x-> 1+(12+(65+(208+(429+(572+429*x)*x)*x)
%p A194719                           *x)*x)*x)(n-1)):
%p A194719 seq(a(n), n=0..30);
%Y A194719 Row n=7 of A183134.
%K A194719 nonn
%O A194719 0,3
%A A194719 _Alois P. Heinz_, Sep 02 2011