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Search: id:A123581
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| A123581 |
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a(1) = 3, a(n) = a(n-1) + greatest prime factor of a(n-1). |
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+0
1
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| 3, 6, 9, 12, 15, 20, 25, 30, 35, 42, 49, 56, 63, 70, 77, 88, 99, 110, 121, 132, 143, 156, 169, 182, 195, 208, 221, 238, 255, 272, 289, 306, 323, 342, 361, 380, 399, 418, 437, 460, 483, 506, 529, 552, 575, 598, 621, 644, 667, 696, 725, 754, 783, 812, 841, 870
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(16) = 88 because a(15) is 77 whose largest prime factor is 11 so 77 + 11 = 88
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MATHEMATICA
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a[1] = 3; a[n_] := a[n] = a[n - 1] + FactorInteger[a[n - 1]][[ -1, 1]]; Array[a, 56] (* Robert G. Wilson v *)
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PROGRAM
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(PARI) {print1(a=3, ", "); for(n=2, 57, print1(a=a+vecmax(factor(a)[, 1]), ", "))} - Klaus Brockhaus, Nov 19 2006
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CROSSREFS
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Essentially the same as A036441 and A076271.
Sequence in context: A083354 A156242 A060293 this_sequence A084515 A084525 A130248
Adjacent sequences: A123578 A123579 A123580 this_sequence A123582 A123583 A123584
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KEYWORD
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nonn,easy
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AUTHOR
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Ben Thurston (benthurston27(AT)yahoo.com), Nov 12 2006
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(at)rgwv.com) and Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Nov 18 2006
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