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Search: id:A083793
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| A083793 |
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Numbers n such that n and n-1 have the same prime signature. Numbers not included in A083792. |
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+0
3
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| 3, 15, 22, 34, 35, 39, 45, 58, 86, 87, 94, 95, 117, 119, 123, 134, 136, 142, 143, 146, 159, 172, 178, 202, 203, 206, 214, 215, 218, 219, 231, 254, 286, 297, 299, 302, 303, 327, 333, 335, 382, 388, 394, 395, 430, 435, 446, 447, 454, 482, 502, 515, 527, 538, 543
(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):with(linalg): primesigcheck := proc(n) temp1 := ifactors(n)[2]: temp2 := ifactors(n-1)[2]: ps1 := array(1..nops(temp1)):ps2 := array(1..nops(temp2)): for i from 1 to nops(temp1) do ps1[i] := temp1[i][2] od: for i from 1 to nops(temp2) do ps2[i] := temp2[i][2] od: if equal(ps1, ps2) then RETURN(1) else RETURN(0) fi: end: for n from 2 to 10^3 do if primesigcheck(n) = 1 then printf(`%d, `, n) fi: od:
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MATHEMATICA
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PrimeFactorExponents[n_] := Flatten[ Table[ # [[2]], {1}] & /@ FactorInteger[n]]; Select[ Range[543], PrimeFactorExponents[ # ] == PrimeFactorExponents[ # - 1] & ]
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CROSSREFS
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Cf. A083792.
Adjacent sequences: A083790 A083791 A083792 this_sequence A083794 A083795 A083796
Sequence in context: A087674 A009057 A083795 this_sequence A083934 A072200 A106403
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), May 07 2003
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EXTENSIONS
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Corrected and extended by James A. Sellers (sellersj(AT)math.psu.edu), May 19, 2003
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