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A054842
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If n = a + 10 * b + 100 * c + 1000 * d + ... then a(n) = (2^a) * (3^b) * (5^c) * (7^d) * ...
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8
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1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 3, 6, 12, 24, 48, 96, 192, 384, 768, 1536, 9, 18, 36, 72, 144, 288, 576, 1152, 2304, 4608, 27, 54, 108, 216, 432, 864, 1728, 3456, 6912, 13824, 81, 162, 324, 648, 1296, 2592, 5184, 10368, 20736, 41472, 243, 486, 972
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| a((10^k-1)/9) = Primorial (k)= A061509((10^k-1)/9). This is a rearrangement of whole numbers. a(m) = a(n) iff m = n. (Unlike A061509, in which a(n) = a(n*10^k)).) - Amarnath Murthy and Meenakshi Srikanth (amarnath_murthy(AT)yahoo.com), Jul 14 2003
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LINKS
| R. Zumkeller, Table of n, a(n) for n = 0..9999 [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 13 2010]
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FORMULA
| a(n) = f(n, 1, 1) with f(x, y, z) = if x > 0 then f(floor(x/10), y*prime(z)^(x mod 10), z+1) else y. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 13 2010]
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EXAMPLE
| a(15)=96 because 3^1 * 2^5 = 3*32 = 96
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CROSSREFS
| Cf. A054841, A085840.
Cf. A019565, A101278. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 13 2010]
Sequence in context: A189398 A086066 A085941 * A101440 A126605 A072067
Adjacent sequences: A054839 A054840 A054841 * A054843 A054844 A054845
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KEYWORD
| base,nonn
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AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Apr 11 2000
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