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Search: id:A060072
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| A060072 |
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a(n) = (n^(n-1)-1)/(n-1). |
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+0
8
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| 0, 1, 4, 21, 156, 1555, 19608, 299593, 5380840, 111111111, 2593742460, 67546215517, 1941507093540, 61054982558011, 2085209001813616, 76861433640456465, 3041324492229179280, 128583032925805678351
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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(n-1)-digit repunits in base n written in decimal.
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FORMULA
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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
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EXAMPLE
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a(10)=111111111; i.e. just nine 1's (converted from base 10 to decimal)
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CROSSREFS
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a(n) = A060071(n)/(n-1) = A060073(n)*(n-1) = A023037(n)-A000169(n)
Cf. A055869.
Adjacent sequences: A060069 A060070 A060071 this_sequence A060073 A060074 A060075
Sequence in context: A006879 A006153 A025164 this_sequence A107872 A008858 A078670
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KEYWORD
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nonn
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AUTHOR
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Henry Bottomley (se16(AT)btinternet.com), Feb 21 2001
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