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A110595 a(1)=5. For n > 1, a(n) = 4*5^(n-1) = A005054(n). 2
5, 20, 100, 500, 2500, 12500, 62500, 312500, 1562500, 7812500, 39062500, 195312500, 976562500, 4882812500, 24414062500, 122070312500, 610351562500, 3051757812500, 15258789062500, 76293945312500, 381469726562500 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) is the total number of holes in all nonnegative n-digit integers. For example, 0, 6 and 9 have 1 hole, while 8 has 2 holes. That adds up to a total of 5 for 1-digit integers. - Tanya Khovanova, Sep 18 2007

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

FORMULA

O.g.f.: 5*x*(1-x)/(1-5*x). - Better definition from R. J. Mathar, May 13 2008

MATHEMATICA

Join[{5}, NestList[5#&, 20, 20]] (* Harvey P. Dale, Jun 19 2013 *)

Rest[CoefficientList[Series[5 x (1 - x)/(1 - 5 x), {x, 0, 50}], x]] (* G. C. Greubel, Sep 01 2017 *)

PROG

(PARI) x='x+O('x^50); Vec(5*x*(1-x)/(1-5*x)) \\ G. C. Greubel, Sep 01 2017

CROSSREFS

Cf. A000351, A007091, A081604, A110591, A110592, A110593, A110594.

Sequence in context: A272218 A026118 A108509 * A092640 A165961 A276314

Adjacent sequences:  A110592 A110593 A110594 * A110596 A110597 A110598

KEYWORD

easy,less,nonn

AUTHOR

Jonathan Vos Post, Jul 29 2005

EXTENSIONS

Better definition from R. J. Mathar, May 13 2008

STATUS

approved

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Last modified July 31 20:24 EDT 2021. Contains 346377 sequences. (Running on oeis4.)