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Search: id:A086806
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| A086806 |
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Sarrus numbers n such that n-1 and n+1 have the same number of prime divisors (counted with multiplicity). |
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+0
1
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| 341, 13747, 19951, 35333, 60787, 137149, 150851, 387731, 458989, 617093, 769757, 1104349, 1251949, 1277179, 1397419, 1463749, 1507963, 1826203, 2134277, 2205967, 2617451, 2976487, 3345773, 4361389, 6474691, 6955541, 8095447
(list; graph; listen)
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OFFSET
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0,1
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EXAMPLE
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341 is a pseudo-prime to base 2 while 340 = 2^2*5*17 and 342 = 2*3^2*19 each have four primes dividing them.
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MATHEMATICA
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PrimeFactorExponentsAdded[n_] := Plus @@ Flatten[ Table[ # [[2]], {1}] & /@ FactorInteger[n]]; Select[ Range[9224390], !PrimeQ[ # ] && PowerMod[2, # - 1, # ] == 1 && PrimeFactorExponentsAdded[ # - 1] == PrimeFactorExponentsAdded[ # + 1] & ]
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CROSSREFS
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Cf. A001222, A001567.
Sequence in context: A143688 A086250 A069309 this_sequence A006107 A015371 A163582
Adjacent sequences: A086803 A086804 A086805 this_sequence A086807 A086808 A086809
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KEYWORD
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nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Aug 05 2003
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 13 2003
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