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A093141 Expansion of (1-6x)/(1-10x). 2
1, 4, 40, 400, 4000, 40000, 400000, 4000000, 40000000, 400000000, 4000000000, 40000000000, 400000000000, 4000000000000, 40000000000000, 400000000000000, 4000000000000000, 40000000000000000, 400000000000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Partial sums are A093140. A convex combination of 10^n and 0^n.

LINKS

Table of n, a(n) for n=0..18.

Index entries for linear recurrences with constant coefficients, signature (10).

FORMULA

a(n) = 4*10^n/10 + 6*0^n/10.

a(n) = phi(10^n). - Paul Barry, Jul 02 2007

a(n) = 4*10^(n-1), n>0. - Vincenzo Librandi, Aug 02 2010

MATHEMATICA

Table[EulerPhi[10^n], {n, 0, 40}] (* Vladimir Joseph Stephan Orlovsky, Nov 10 2009 *)

Join[{1}, NestList[10#&, 4, 20]] (* Harvey P. Dale, Apr 01 2018 *)

PROG

(PARI) Vec((1-6*x)/(1-10*x) + O(x^30)) \\ Michel Marcus, Jan 17 2015

CROSSREFS

Sequence in context: A155641 A122652 A299867 * A220965 A278036 A221588

Adjacent sequences:  A093138 A093139 A093140 * A093142 A093143 A093144

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Mar 24 2004

STATUS

approved

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Last modified September 17 04:03 EDT 2019. Contains 327119 sequences. (Running on oeis4.)