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Search: id:A089906
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| A089906 |
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Sum of digits of numbers between 0 and (4/9)*(10^n-1). |
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+0
7
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| 0, 10, 270, 4650, 66430, 864210, 10641990, 126419770, 1464197550, 16641975330, 186419753110, 2064197530890, 22641975308670, 246419753086450, 2664197530864230, 28641975308642010, 306419753086419790
(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(4, 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, A089907, A089908, A089909, A034967.
Sequence in context: A003388 A055408 A166811 this_sequence A084943 A055055 A153331
Adjacent sequences: A089903 A089904 A089905 this_sequence A089907 A089908 A089909
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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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