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Search: id:A140831
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| A140831 |
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Let p^b(n,p) be the largest power of the prime p that divides n. The integer n is included if the list of p^b(n,p)'s, where each p is a distinct prime divisor of n, arranged by size of each p^b(n,p) is not in the same order as the list of p^b(n,p)'s arranged by size of each prime p. |
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+0
1
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| 12, 24, 40, 45, 48, 56, 60, 63, 80, 84, 90, 96, 112, 120, 126, 132, 135, 144, 156, 160, 168, 175, 176, 180, 189, 192, 204, 208, 224, 228, 240, 252, 264, 270, 275, 276, 280, 288, 297, 300, 312, 315, 320, 325, 336, 348, 350, 351, 352, 360, 372, 378, 384, 405
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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This sequence contains no squarefree integers.
90 is the smallest integer in this sequence but not in sequence A126855.
The number of terms < 10^n: 0, 12, 151, 1575, 16154, 161630, 1617052,..., . - Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 31 2008
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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The prime-factorization of 90 is, when arranged by size of the distinct primes, 2^1 * 3^2 * 5^1. Since 3^2 is > 5^1, even though 5 > 3, then 90 is in the sequence.
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MATHEMATICA
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fQ[n_] := Block[{f = First@# ^ Last@# & /@ FactorInteger@n}, f != Sort@f]; Select[ Range@ 407, fQ@# &] - Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 31 2008
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CROSSREFS
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Cf. A141809, A141810, A126855.
Sequence in context: A098242 A101425 A139406 this_sequence A126855 A102749 A085231
Adjacent sequences: A140828 A140829 A140830 this_sequence A140832 A140833 A140834
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Jul 18 2008
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 31 2008
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