A126882 a(1)=2. a(n) is the a(n-1)st integer from among those positive integers coprime to a(n-1).

2, 3, 4, 7, 8, 15, 28, 65, 87, 134, 271, 272, 577, 578, 1227, 1844, 3695, 4624, 9825, 18562, 37127, 37537, 37538, 75627, 113480, 283799, 283800, 1198543, 1201967, 1302144, 3907583, 3907584, 11948189, 13143019, 13151298, 39453911, 46029570

Offset

1,1

Links

Table of n, a(n) for n=1..37.

Formula

a(n) = A069213(a(n-1)).

Example

a(4)=7. So a(5) is the 7th positive integer which is coprime to 7. 7 is coprime to 1,2,3,4,5,6,8,9,10,... So a(5) is the 7th of these, which is 8.

Mathematica

f[n_] := Block[{k = 0, c = n}, While[c > 0, k++; While[GCD[k, n] > 1, k++ ]; c--; ]; k]; g[l_] := Append[l, f[l[[ -1]]]]; Nest[g, {2}, 36] (* Ray Chandler, Dec 31 2006 *)

Crossrefs

Cf. A069213, A126881.

Sequence in context: A370858 A126850 A007497 * A333801 A239973 A281782

Adjacent sequences: A126879 A126880 A126881 * A126883 A126884 A126885

Keyword

nonn

Author

Leroy Quet, Dec 29 2006

Extensions

Extended by Ray Chandler, Dec 31 2006

Status

approved