A123089 a(1)=1. For n>=2, a(n) = n + (largest divisor of n which occurs among the earlier terms of the sequence).

1, 3, 6, 5, 10, 12, 8, 16, 12, 20, 12, 24, 14, 28, 20, 32, 18, 36, 20, 40, 24, 23, 46, 48, 30, 27, 54, 56, 30, 60, 32, 64, 36, 35, 70, 72, 38, 76, 42, 80, 42, 84, 44, 88, 50, 92, 48, 96, 50, 100, 54, 53, 106, 108, 60, 112, 60, 59, 118, 120, 62, 124, 66, 128, 70, 132, 68, 136

Offset

1,2

Links

Table of n, a(n) for n=1..68.

Example

The largest divisor of 9 which occurs among the first 8 terms of the sequence is 3. So a(9) = 9 + 3 = 12.

Mathematica

f[l_List] := Block[{n = Length[l] + 1}, Append[l, n + Max[Select[l, Mod[n, # ] == 0 &]]]]; Nest[f, {1}, 100] (* Ray Chandler, Sep 30 2006 *)

Crossrefs

Sequence in context: A298818 A196068 A242239 * A246978 A127780 A350661

Adjacent sequences: A123086 A123087 A123088 * A123090 A123091 A123092

Keyword

nonn

Author

Leroy Quet, Sep 27 2006

Extensions

Extended by Ray Chandler, Sep 30 2006

Status

approved