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Search: id:A089908
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| A089908 |
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Sum of digits of numbers between 0 and (7/9)*(10^n-1). |
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+0
7
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| 0, 28, 609, 9555, 130501, 1654947, 20049393, 235493839, 2704938285, 30549382731, 340493827177, 3754938271623, 41049382716069, 445493827160515, 4804938271604961, 51549382716049407, 550493827160493853
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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From a suggestion of Yalcin Aktar (aktaryalcin(AT)msn.com)
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FORMULA
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a(n)=s(7, n-1) where s(a, k)=a*(k+1)+a^2*sum(i=0, k, i*10^(k-i))+sum(i=0, k, 5*a*(9*(k-i)+a- 1)*10^(k-i-1))
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CROSSREFS
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Cf. A089903, A089904, A089905, A087330, A089906, A089907, A089909, A034967.
Sequence in context: A107397 A053110 A004371 this_sequence A038121 A070310 A160141
Adjacent sequences: A089905 A089906 A089907 this_sequence A089909 A089910 A089911
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KEYWORD
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nonn,base
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 14 2003
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