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Search: id:A000422
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| A000422 |
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Concatenation of numbers from n down to 1. |
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+0
38
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| 1, 21, 321, 4321, 54321, 654321, 7654321, 87654321, 987654321, 10987654321, 1110987654321, 121110987654321, 13121110987654321, 1413121110987654321, 151413121110987654321, 16151413121110987654321
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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The first prime term in this sequence is A000422(82) - Artur Jasinski (grafix(AT)csl.pl), Mar 30 2008
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REFERENCES
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F. Smarandache, "Properties of the Numbers", University of Craiova Archives, 1975; Arizona State University Special Collections, Tempe, AZ
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LINKS
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M. L. Perez et al., eds., Smarandache Notions Journal
R. W. Stephan, Factors and primes in two Smarandache sequences
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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FORMULA
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a(n+1) = (n+1)*10^len(a(n)) + a(n), where len(k) = number of digits in k.
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MATHEMATICA
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b = {}; a = {}; Do[w = RealDigits[n]; w = First[w]; Do[PrependTo[a, w[[Length[w] - k + 1]]], {k, 1, Length[w]}]; p = FromDigits[a]; AppendTo[b, p], {n, 1, 30}]; b (*Artur Jasinski*) - Artur Jasinski (grafix(AT)csl.pl), Mar 30 2008
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CROSSREFS
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Cf. A000422, A116504, A007908, A116505, A104759, A138789, A138790, A138793.
Sequence in context: A104759 A138793 A014925 this_sequence A060554 A057610 A036737
Adjacent sequences: A000419 A000420 A000421 this_sequence A000423 A000424 A000425
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KEYWORD
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nonn,base
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AUTHOR
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R. Muller
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