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A125843
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a(1)=1. a(n) = the sum of the terms from among the first floor(n/2) terms of the sequence which are coprime to n.
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1
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1, 1, 1, 2, 2, 3, 3, 3, 5, 3, 7, 3, 10, 9, 7, 12, 16, 8, 21, 15, 12, 27, 31, 15, 29, 30, 29, 32, 53, 17, 60, 46, 36, 46, 59, 22, 96, 67, 60, 62, 132, 8, 144, 109, 45, 140, 202, 53, 182, 149, 120, 184, 276, 111, 230, 178, 181, 208, 390, 176, 407, 252, 237, 283, 378, 181
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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EXAMPLE
| The first floor(15/2) terms of the sequence are 1,1,1,2,2,3,3. Of these, five terms (1,1,1,2,2) are coprime to 15. So a(15) = 1+1+1+2+2 = 7.
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MATHEMATICA
| f[l_List] := Block[{n = Length[l] + 1}, Append[l, Plus @@ Select[Take[l, Floor[n/2]], GCD[ #, n] == 1 &]]]; Nest[f, {1}, 65] (*Chandler*)
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CROSSREFS
| Cf. A125842.
Sequence in context: A110876 A136132 A136545 * A147665 A127332 A087826
Adjacent sequences: A125840 A125841 A125842 * A125844 A125845 A125846
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Dec 10 2006
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Dec 11 2006
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