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 A132851 a(0)=1. a(n) = the largest squarefree integer which divides (n+a(n-1)), for n>=1. 0

%I

%S 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,

%T 53,3,2,2,33,65,14,6,41,77,114,38,77,39,10,26,69,113,158,102,149,197,

%U 246,74,5,57,110,82,137,193,10,34,93,51,14,38,101,165,230,74,141,209,278

%N a(0)=1. a(n) = the largest squarefree integer which divides (n+a(n-1)), for n>=1.

%e 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.

%t 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_, Dec 19 2007 *)

%Y Cf. A007947.

%K nonn

%O 0,2

%A _Leroy Quet_, Nov 21 2007

%E More terms from _Stefan Steinerberger_, Dec 19 2007

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Last modified April 7 10:46 EDT 2020. Contains 333301 sequences. (Running on oeis4.)