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Triangle of coefficients in expansion of (1+8x)^n.
2

%I #16 Jul 25 2015 13:24:10

%S 1,1,8,1,16,64,1,24,192,512,1,32,384,2048,4096,1,40,640,5120,20480,

%T 32768,1,48,960,10240,61440,196608,262144,1,56,1344,17920,143360,

%U 688128,1835008,2097152,1,64,1792,28672,286720,1835008,7340032,16777216,16777216

%N Triangle of coefficients in expansion of (1+8x)^n.

%C T(n,k) equals the number of n-length words on {0,1,...,8} having n-k zeros. - _Milan Janjic_, Jul 24 2015

%F G.f.: 1 / [1 - x(1+8y)].

%F T(n,k) = 8^k*C(n,k) = Sum_{i=n-k..n} C(i,n-k)*C(n,i)*7^(n-i). Row sums are 9^n = A001019. - _Mircea Merca_, Apr 28 2012

%p T:= n-> (p-> seq(coeff(p, x, k), k=0..n))((1+8*x)^n):

%p seq(T(n), n=0..10); # _Alois P. Heinz_, Jul 25 2015

%K tabl,nonn,easy

%O 0,3

%A _N. J. A. Sloane_.