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A046758
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Equidigital numbers.
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8
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1, 2, 3, 5, 7, 10, 11, 13, 14, 15, 16, 17, 19, 21, 23, 25, 27, 29, 31, 32, 35, 37, 41, 43, 47, 49, 53, 59, 61, 64, 67, 71, 73, 79, 81, 83, 89, 97, 101, 103, 105, 106, 107, 109, 111, 112, 113, 115, 118, 119, 121, 122, 123, 127, 129, 131, 133, 134, 135, 137, 139
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Write n as product of primes raised to powers, let D(n) = A050252 = total number of digits in product representation (number of digits in all the primes plus number of digits in all the exponents that are greater than 1) and l(n) = number of digits in n; sequence gives n such that D(n)=l(n).
A050252(a(n)) = A055642(a(n)). [Reinhard Zumkeller, Jun 21 2011]
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LINKS
| J. P. Delahaye, "Primes Hunters", Economical and Prodigal Numbers (Text in French)
R. G. E. Pinch, Economical numbers.
Eric Weisstein's World of Mathematics, Equidigital Number.
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
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EXAMPLE
| For n=125=5^3, l(n)=3 but D(n)=2.
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PROG
| (Haskell)
a046758 n = a046758_list !! (n-1)
a046758_list = filter (\n -> a050252 n == a055642 n) [1..]
-- Reinhard Zumkeller, Jun 21 2011
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CROSSREFS
| Cf. A046759, A046760, A050252, A073048.
Sequence in context: A163975 A202267 A125975 * A121232 A122428 A087246
Adjacent sequences: A046755 A046756 A046757 * A046759 A046760 A046761
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KEYWORD
| nonn,base,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Eric Weisstein (eric(AT)weisstein.com)
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