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Search: id:A122456
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| A122456 |
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a(0)=1, a(1)=1; for n>1, a(n) = the sum of the two largest earlier terms which are both coprime to n. |
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+0
2
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| 1, 1, 2, 3, 4, 7, 8, 12, 10, 18, 10, 30, 8, 48, 4, 16, 10, 78, 8, 126, 10, 26, 10, 204, 8, 330, 10, 42, 4, 534, 8, 864, 10, 42, 10, 1398, 8, 2262, 10, 26, 10, 3660, 2, 5922, 10, 52, 10, 5922, 8, 5922, 10, 78, 10, 11844, 8, 17766, 4, 78, 10, 29610, 8, 47376, 10, 78, 10
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OFFSET
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0,3
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EXAMPLE
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a(0)=1, a(1)=1, a(5)=7 are the terms which are coprime to 12 and which occur among {a(0),a(1),...a(11)}. 1 and 7 are the two largest of these terms, so a(12) = 1 + 7 = 8.
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MATHEMATICA
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f[s_] := Append[s, Plus @@ Take[Sort[Select[s, GCD[ #, Length[s]] == 1 &]], -2]]; Nest[f, {1, 1}, 64] (*Chandler*)
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CROSSREFS
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Cf. A122457.
Sequence in context: A003508 A078662 A050048 this_sequence A073882 A015840 A051213
Adjacent sequences: A122453 A122454 A122455 this_sequence A122457 A122458 A122459
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Sep 07 2006
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net) and Robert G. Wilson v, Sep 11 2006
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