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

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

Offset

0,2

Links

Table of n, a(n) for n=0..69.

Example

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.

Mathematica

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 *)

Crossrefs

Cf. A007947.

Sequence in context: A135376 A132850 A076561 * A361119 A293833 A146316

Adjacent sequences: A132848 A132849 A132850 * A132852 A132853 A132854

Keyword

nonn

Author

Leroy Quet, Nov 21 2007

Extensions

More terms from Stefan Steinerberger, Dec 19 2007

Status

approved