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Search: id:A162687
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| A162687 |
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Write the distinct primes dividing n down in binary, in order with the largest prime on the left and smallest on the right. Concatenate, and convert to decimal to get a(n). |
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+0
1
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| 0, 2, 3, 2, 5, 14, 7, 2, 3, 22, 11, 14, 13, 30, 23, 2, 17, 14, 19, 22, 31, 46, 23, 14, 5, 54, 3, 30, 29, 62, 31, 2, 47, 70, 61, 14, 37, 78, 55, 22, 41, 62, 43, 46, 23, 94, 47, 14, 7, 22, 71, 54, 53, 14, 93, 30, 79, 118, 59, 62, 61, 126, 31, 2, 109, 62, 67, 70, 95, 182, 71, 14, 73
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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60 is factored as 5 * 3 * 2^2. Write down the distinct prime divisors (largest to smallest) in binary to get 101, 11, 10. Concatenate to get 1011110. a(60) is the decimal equivalent of this, which is 94.
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MAPLE
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A162687 := proc(n) local pfs, bdgs, d; if n = 1 then RETURN(0); fi; pfs := numtheory[factorset](n) ; pfs := sort(convert(pfs, list)) ; bdgs := convert(op(1, pfs), base, 2) ; for d from 2 to nops(pfs) do bdgs := [op(bdgs), op(convert(op(2, pfs), base, 2))] ; od: add(op(i, bdgs)*2^(i-1), i=1..nops(bdgs)) ; end: seq(A162687(n), n=1..100) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 16 2009]
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CROSSREFS
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Sequence in context: A147294 A059098 A082050 this_sequence A010242 A086507 A133568
Adjacent sequences: A162684 A162685 A162686 this_sequence A162688 A162689 A162690
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KEYWORD
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base,nonn
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AUTHOR
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Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Jul 10 2009
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EXTENSIONS
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Extended beyond a(16) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 16 2009
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