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A060072
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a(n) = (n^(n-1)-1)/(n-1).
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12
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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; internal format)
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OFFSET
| 1,3
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COMMENTS
| (n-1)-digit repunits in base n written in decimal.
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,200
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FORMULA
| a(n) = sum( n^(k-1) C(n, k) ), k=1..n - Olivier Gerard (olivier.gerard(AT)gmail.com), Jun 26 2001
sum (n^(n-j),j=2..n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 11 2006
a(n+1) = A125118(n,n). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 21 2006
a(n)=Integral_{x=1/n..1} 1/x^n dx. [From Francesco Daddi (francesco.daddi(AT)libero.it, Aug 01 2011]
a(n) = A037205(n-1)/(n-1) = A060073(n)*(n-1) = A023037(n)-A000169(n)
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EXAMPLE
| a(10)=111111111; i.e. just nine 1's (converted from base 10 to decimal)
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MAPLE
| a:=n->sum ((n+2)^j, j=0..n): seq(a(n), n=-1..17); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 17 2008]
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MATHEMATICA
| A060072[n_] := (n^(n - 1) - 1)/(n - 1); A060072[1] = 0; Table[A060072[n], {n, 2, 30}] (* From Vladimir Joseph Stephan Orlovsky, Jul 22 2011 *)
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PROG
| (PARI) { write("b060072.txt", "1 0"); for (n=2, 200, write("b060072.txt", n, " ", (n^(n - 1) - 1)/(n - 1)); ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 01 2009]
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CROSSREFS
| Cf. A055869.
Sequence in context: A183387 A025164 A166901 * A157503 A144010 A179496
Adjacent sequences: A060069 A060070 A060071 * A060073 A060074 A060075
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KEYWORD
| nonn
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AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Feb 21 2001
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