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Search: id:A127075
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| A127075 |
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a(1)=1. a(n) = a(n-1) + (sum of the earlier terms {among terms a(1) through a(n-1)} which are coprime to n). |
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+0
2
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| 1, 2, 5, 11, 25, 67, 178, 287, 863, 2092, 5612, 6871, 22885, 53613, 69597, 223822, 385931, 802877, 2308019, 5936156, 12937623, 29456690, 81587807, 166703456, 437728341, 973247233, 2233938123, 4919445412, 13784085189, 14842425156
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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The terms of the sequence, among terms a(1) through a(5), which are coprime to 6 are a(1)=1, a(3)=5, a(4)=11 and a(5)=25. So a(6) = a(5) +1 +5 +11 +25 = 67.
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MATHEMATICA
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f[l_List] := Append[l, l[[ -1]] + Plus @@ Select[l, GCD[ #, Length[l] + 1] == 1 &]]; Nest[f, {1}, 30] (*Chandler*)
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CROSSREFS
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Cf. A127076.
Adjacent sequences: A127072 A127073 A127074 this_sequence A127076 A127077 A127078
Sequence in context: A106336 A047775 A001432 this_sequence A053429 A104237 A085945
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Jan 04 2007
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 06 2007
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