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A133439
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a(1)=1. a(n) = sum{1<=k<=n, GCD(k,n)=1} a(floor(sqrt(k))).
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1, 1, 2, 2, 4, 2, 6, 4, 6, 5, 12, 5, 16, 9, 11, 12, 24, 9, 28, 13, 19, 16, 36, 13, 33, 22, 34, 25, 56, 16, 64, 36, 46, 38, 56, 29, 86, 44, 56, 37, 94, 28, 98, 46, 55, 52, 106, 37, 95, 49, 80, 64, 134, 49, 107, 67, 106, 82, 170, 46, 182, 94, 111, 104, 149, 63, 212, 104, 146, 78
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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EXAMPLE
| The positive integers which are <12 and are coprime to 12 are 1,5,7,11. The floors of the squareroots of these are 1,2,2,3. So a(12) = a(1)+a(2)+a(2)+a(3) = 1+1+1+2 = 5.
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MATHEMATICA
| a = {1}; Do[s = 0; For[j = 1, j < n, j++, If[GCD[j, n] == 1, s = s + a[[Floor[Sqrt[j]]]]]]; AppendTo[a, s], {n, 2, 80}]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 19 2007
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CROSSREFS
| Sequence in context: A122646 A028496 A063428 * A072300 A028913 A185048
Adjacent sequences: A133436 A133437 A133438 * A133440 A133441 A133442
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Nov 26 2007
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EXTENSIONS
| More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 19 2007
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