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Search: id:A007091
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| A007091 |
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Numbers in base 5.
(Formerly M0595)
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+0
25
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| 0, 1, 2, 3, 4, 10, 11, 12, 13, 14, 20, 21, 22, 23, 24, 30, 31, 32, 33, 34, 40, 41, 42, 43, 44, 100, 101, 102, 103, 104, 110, 111, 112, 113, 114, 120, 121, 122, 123, 124, 130, 131, 132, 133, 134, 140, 141, 142, 143, 144, 200, 201, 202, 203, 204, 210, 211, 212, 213
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Contribution from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jun 25 2009: (Start)
Nonnegative integers with no decimal digit > 4.
Thus nonnegative integers in base 10 whose doubling by normal addition or multiplication requires no carry operation. (End)
It appears that this sequence corresponds to the numbers n for which twice the sum of digits of n is the sum of digits of 2*n. [From Remy Sigrist (remysigrist(AT)free.fr), Nov 22 2009]
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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FORMULA
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a(0)=0 a(n)=10*a(n/5) if n==0 (mod 5) a(n)=a(n-1)+1 otherwise. - Benoit Cloitre, Dec 22, 2002
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MATHEMATICA
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Table[ FromDigits[ IntegerDigits[n, 5]], {n, 0, 60}]
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PROGRAM
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(PARI) a(n)=if(n<1, 0, if(n%5, a(n-1)+1, 10*a(n/5)))
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CROSSREFS
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Cf. A000042, A007088, A007089, A007090, A007092, A007093, A007094 & A007095.
Sequence in context: A098892 A037325 A037469 this_sequence A058185 A080897 A117383
Adjacent sequences: A007088 A007089 A007090 this_sequence A007092 A007093 A007094
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KEYWORD
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nonn,base
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Robert G. Wilson v (rgwv(AT)rgwv.com)
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