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Expansion of (1-3x)/(1-10x).
5

%I #20 Apr 09 2024 05:13:07

%S 1,7,70,700,7000,70000,700000,7000000,70000000,700000000,7000000000,

%T 70000000000,700000000000,7000000000000,70000000000000,

%U 700000000000000,7000000000000000,70000000000000000,700000000000000000,7000000000000000000,70000000000000000000

%N Expansion of (1-3x)/(1-10x).

%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (10).

%F a(0) = 1, a(n) = 7*10^(n-1) for n>0.

%F a(n) = Sum_{k=0..n} A193722(n,k)*3^k.

%t CoefficientList[Series[(1-3x)/(1-10x),{x,0,20}],x] (* or *) LinearRecurrence[ {10},{1,7},30] (* or *) Join[{1},NestList[10#&,7,20]] (* _Harvey P. Dale_, Dec 18 2021 *)

%Y Cf. A002001, A193722, A196661.

%K nonn,easy

%O 0,2

%A _Philippe Deléham_, Oct 05 2011