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Search: id:A132851
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| A132851 |
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a(0)=1. a(n) = the largest squarefree integer which divides (n+a(n-1)), for n>=1. |
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+0
1
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| 1, 2, 2, 5, 3, 2, 2, 3, 11, 10, 10, 21, 33, 46, 30, 15, 31, 6, 6, 5, 5, 26, 6, 29, 53, 78, 26, 53, 3, 2, 2, 33, 65, 14, 6, 41, 77, 114, 38, 77, 39, 10, 26, 69, 113, 158, 102, 149, 197, 246, 74, 5, 57, 110, 82, 137, 193, 10, 34, 93, 51, 14, 38, 101, 165, 230, 74, 141, 209, 278
(list; graph; listen)
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OFFSET
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0,2
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EXAMPLE
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a(8) + 9 = 11 + 9 = 20. 20 = 2^2 *5, so the largest squarefree divisor of 20 is 2*5 = 10. a(9) is therefore 10.
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MATHEMATICA
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a[n_] := If[Max[Table[FactorInteger[n][[i, 2]], {i, 1, Length[FactorInteger[n]]}]] > 1, 0, 1]; b = {1}; Do[AppendTo[b, Select[Divisors[j + b[[ -1]]], a[ # ] == 1 &][[ -1]]], {j, 1, 100}]; b - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 19 2007
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CROSSREFS
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Cf. A007947.
Sequence in context: A135376 A132850 A076561 this_sequence A146316 A128134 A130327
Adjacent sequences: A132848 A132849 A132850 this_sequence A132852 A132853 A132854
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Nov 21 2007
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Dec 19 2007
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