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Search: id:A157487
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| A157487 |
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Numbers n such that n-+1 are divisible by exactly 7 primes, counted with multiplicity. |
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+0
1
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| 10529, 15391, 17983, 18751, 22049, 23489, 24751, 26081, 29249, 32561, 35153, 43471, 49951, 52975, 58049, 58481, 67229, 67231, 70687, 71873, 72415, 76049, 77921, 79001, 79649, 82783, 83249, 85751, 88289, 93799, 95551, 97471, 102545
(list; graph; listen)
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OFFSET
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1,1
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MAPLE
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with(numtheory): a := proc (n) if bigomega(n-1) = 7 and bigomega(n+1) = 7 then n else end if end proc: seq(a(n), n = 2 .. 120000); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 07 2009]
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MATHEMATICA
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q=7; lst={}; Do[If[Plus@@Last/@FactorInteger[n-1]==q&&Plus@@Last/@FactorInteger[n+1]==q, AppendTo[lst, n]], {n, 9!}]; lst
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CROSSREFS
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Cf. A124936, A014612, A157483, A157484, A157485, A157486
Sequence in context: A068759 A114126 A120500 this_sequence A119866 A065319 A063060
Adjacent sequences: A157484 A157485 A157486 this_sequence A157488 A157489 A157490
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KEYWORD
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nonn
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), Mar 01 2009
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 07 2009
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