A122456 a(0)=1, a(1)=1; for n>1, a(n) = the sum of the two largest earlier terms which are both coprime to n.

1, 1, 2, 3, 4, 7, 8, 12, 10, 18, 10, 30, 8, 48, 4, 16, 10, 78, 8, 126, 10, 26, 10, 204, 8, 330, 10, 42, 4, 534, 8, 864, 10, 42, 10, 1398, 8, 2262, 10, 26, 10, 3660, 2, 5922, 10, 52, 10, 5922, 8, 5922, 10, 78, 10, 11844, 8, 17766, 4, 78, 10, 29610, 8, 47376, 10, 78, 10

Offset

0,3

Links

Table of n, a(n) for n=0..64.

Example

a(0)=1, a(1)=1, a(5)=7 are the terms which are coprime to 12 and which occur among {a(0),a(1),...a(11)}. 1 and 7 are the two largest of these terms, so a(12) = 1 + 7 = 8.

Mathematica

f[s_] := Append[s, Plus @@ Take[Sort[Select[s, GCD[ #, Length[s]] == 1 &]], -2]]; Nest[f, {1, 1}, 64] (* Ray Chandler, Sep 11 2006 *)

Crossrefs

Cf. A122457.

Sequence in context: A256219 A078662 A050048 * A186243 A073882 A015840

Adjacent sequences: A122453 A122454 A122455 * A122457 A122458 A122459

Keyword

nonn

Author

Leroy Quet, Sep 07 2006

Extensions

Extended by Ray Chandler and Robert G. Wilson v, Sep 11 2006

Status

approved