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A162146
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a(n) = the smallest positive integer divisible by exactly n distinct primes, where each of these primes has the same number of digits when written in binary.
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0
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1, 2, 6, 7429, 215441, 6678671, 9586934839, 584803025179, 1985383050388741, 204494454190040323, 21880906598334314561, 2385018819218440287149, 269507126571683752447837, 34227405074603836560875299
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Each term of this sequence is squarefree.
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EXAMPLE
| For a(2), 6 = 2 (10_b) * 3 (11_b), For a(3), 7429 = 17 (10001_b) * 19 (10011_b) * 23 (10111_b), For a(4), 215441 = 17 (10001_b) * 19 (10011_b) * 23 (10111_b) * 29 (11101_b), etc. [From Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 16 2009]
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MATHEMATICA
| f[n_] := Block[{k = 1}, While[p = Select[ Table[i, {i, 2^k, 2^(k + 1) - 1}], PrimeQ@# &]; len = Length@p; len < n, k++ ]; Times @@ Take[p, n]]; Table[ f@n, {n, 0, 15}] [From Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 16 2009]
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CROSSREFS
| A162145
Sequence in context: A071093 A114045 A116899 * A055698 A121167 A115658
Adjacent sequences: A162143 A162144 A162145 * A162147 A162148 A162149
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KEYWORD
| base,nonn
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AUTHOR
| Leroy Quet, Jun 25 2009
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 16 2009
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