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Search: id:A087330
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| A087330 |
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Sum of all digits of all integers less than or equal to 555...55 (with n 5's) in base 10. |
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+0
8
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| 0, 15, 370, 6150, 86430, 1114210, 13641990, 161419770, 1864197550, 21141975330, 236419753110, 2614197530890, 28641975308670, 311419753086450, 3364197530864230, 36141975308642010, 386419753086419790
(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)=20/9*n-110/81*10^n+110/81+5/2*n*10^n (formula from B. Greco)
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EXAMPLE
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a(1)=15 since numbers less than or equal to 5 are 1,2,3,4,5 and the sum of digits is 1+2+3+4+5=15.
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CROSSREFS
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Sequence in context: A030049 A012486 A035020 this_sequence A035274 A129615 A069990
Adjacent sequences: A087327 A087328 A087329 this_sequence A087331 A087332 A087333
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KEYWORD
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base,nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Oct 20 2003
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