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Search: id:A076136
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| A076136 |
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Numbers n such that Omega(n) = Omega(n-1) + Omega(n-2), where Omega(n) (A001222) denotes the number of prime factors of n, counting multiplicity. |
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+0
3
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| 3, 4, 8, 12, 16, 36, 40, 54, 63, 75, 88, 104, 112, 132, 135, 140, 150, 195, 200, 204, 208, 220, 252, 279, 280, 294, 328, 375, 390, 399, 405, 408, 416, 423, 444, 456, 464, 486, 510, 516, 520, 525, 558, 560, 592, 612, 615, 616, 620, 630, 636, 644, 656, 663, 680
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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E.g. Omega(3) = 1 + 0 = Omega(2) + Omega(1). Omega(4) = 1 + 1 = Omega(3) + Omega(2).
8 is a term because Omega(8)=3=Omega(7)+Omega(6)=1+2=3
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MATHEMATICA
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Omega[n_] := Apply[Plus, Transpose[FactorInteger[n]][[2]]]; l = {3}; Do[If[Omega[n] == Omega[n - 1] + Omega[n - 2], l = Append[l, n]], {n, 4, 1000}]; l
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PROGRAM
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(PARI) j=[]; for(n=1, 1000, if(bigomega(n)==bigomega(n-1)+bigomega(n-2), j=concat(j, n))); j
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CROSSREFS
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Cf. A076137, A001222.
Sequence in context: A063227 A138926 A077434 this_sequence A146566 A064188 A147620
Adjacent sequences: A076133 A076134 A076135 this_sequence A076137 A076138 A076139
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KEYWORD
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nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Oct 30 2002
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