A093141 Expansion of (1-6x)/(1-10x).

1, 4, 40, 400, 4000, 40000, 400000, 4000000, 40000000, 400000000, 4000000000, 40000000000, 400000000000, 4000000000000, 40000000000000, 400000000000000, 4000000000000000, 40000000000000000, 400000000000000000

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