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A085307
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a(1) = 1; for n>1, concatenate distinct prime-factors of n in decreasing order.
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4
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1, 2, 3, 2, 5, 32, 7, 2, 3, 52, 11, 32, 13, 72, 53, 2, 17, 32, 19, 52, 73, 112, 23, 32, 5, 132, 3, 72, 29, 532, 31, 2, 113, 172, 75, 32, 37, 192, 133, 52, 41, 732, 43, 112, 53, 232, 47, 32, 7, 52, 173, 132, 53, 32, 115, 72, 193, 292, 59, 532, 61, 312, 73, 2, 135, 1132, 67
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| n and a(n) have the same parity.
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FORMULA
| Algorithm: 1# factorize n; 2# prime-factors order by decreasing size; 3# concatenate prime factors and interpret the result as decimal number.
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EXAMPLE
| m=100=2.2.5.5 -> {2,5} -> {5,2} -> 52=a(100); a(510510)=1713117532, while A084317(510510)=2357111317.
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MATHEMATICA
| f[n_] := FromDigits[ Flatten[ IntegerDigits /@ Reverse[ Flatten[ Table[ # [[1]], {1}] & /@ FactorInteger[n]]]]]; Table[ f[n], {n, 1, 70}]
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CROSSREFS
| In A084317 the order of factors is increasing.
Cf. A084317, A084318, A084319, A085308, A085309, A084796, A084797.
Sequence in context: A084317 A037279 A163591 * A078599 A183103 A183105
Adjacent sequences: A085304 A085305 A085306 * A085308 A085309 A085310
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KEYWORD
| base,nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Jun 27 2003
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EXTENSIONS
| Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 15 2003
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