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A060072 a(n) = (n^(n-1) - 1)/(n-1). 13
0, 1, 4, 21, 156, 1555, 19608, 299593, 5380840, 111111111, 2593742460, 67546215517, 1941507093540, 61054982558011, 2085209001813616, 76861433640456465, 3041324492229179280, 128583032925805678351, 5784852794328402307380, 275941052631578947368421 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

(n-1)-digit repunits in base n written in decimal.

LINKS

Harry J. Smith, Table of n, a(n) for n=1,...,200

FORMULA

a(n) = sum_{k=1..n} n^(k-1)*C(n, k). - Olivier Gérard, Jun 26 2001

a(n) = sum_{j=2..n} n^(n-j). - Zerinvary Lajos, Sep 11 2006

a(n+1) = A125118(n,n). - Reinhard Zumkeller, Nov 21 2006

a(n) = Integral_{x=1/n..1} 1/x^n dx. - Francesco Daddi, Aug 01 2011

a(n) = A037205(n-1)/(n-1) = A060073(n)*(n-1) = A023037(n) - A000169(n).

a(n) = [x^n] x^2/((1 - x)*(1 - n*x)). - Ilya Gutkovskiy, Oct 04 2017

EXAMPLE

a(10)=111111111; i.e., just nine 1's (converted from base 10 to decimal).

MAPLE

a:=n->sum ((n+2)^j, j=0..n): seq(a(n), n=-1..17); # Zerinvary Lajos, Dec 17 2008

MATHEMATICA

A060072[n_] := (n^(n - 1) - 1)/(n - 1); A060072[1] = 0; Table[A060072[n], {n, 2, 30}] (* Vladimir Joseph Stephan Orlovsky, Jul 22 2011 *)

Join[{0}, Array[(#^(#-1)-1)/(#-1)&, 20, 2]] (* Harvey P. Dale, Jun 04 2013 *)

PROG

(PARI) { write("b060072.txt", "1 0"); for (n=2, 200, write("b060072.txt", n, " ", (n^(n - 1) - 1)/(n - 1)); ) } \\ Harry J. Smith, Jul 01 2009

CROSSREFS

Cf. A055869.

Sequence in context: A025164 A316370 A166901 * A157503 A144010 A179496

Adjacent sequences:  A060069 A060070 A060071 * A060073 A060074 A060075

KEYWORD

nonn

AUTHOR

Henry Bottomley, Feb 21 2001

STATUS

approved

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Last modified July 20 22:54 EDT 2019. Contains 325189 sequences. (Running on oeis4.)