A157420 a(0)=1. a(n) = the smallest integer coprime to a(n-1) and greater than the n-th Fibonacci number.

1, 2, 3, 4, 5, 6, 11, 14, 23, 35, 57, 91, 145, 234, 379, 611, 989, 1598, 2587, 4182, 6767, 10947, 17713, 28658, 46371, 75026, 121395, 196421, 317812, 514233, 832042, 1346271, 2178310, 3524579, 5702889, 9227467, 14930353, 24157818, 39088171

Offset

0,2

Links

Michael De Vlieger, Table of n, a(n) for n = 0..4786

Example

a(7) = 14, and the 8th Fibonacci number is 21. So for a(8) we want the smallest integer that is both coprime to 14 and is > 21. Checking: 22 is not coprime to 14. But 23 is coprime to 14, so a(8) = 23.

Mathematica

Fold[Append[#1, Block[{k = Fibonacci@ #2 + 1}, While[! CoprimeQ[k, #1[[-1]] ], k++]; k]] &, {1}, Range@ 38] (* Michael De Vlieger, Oct 30 2017 *)

Crossrefs

Cf. A157419, A157421.

Sequence in context: A309548 A088411 A075073 * A221471 A058243 A264665

Adjacent sequences: A157417 A157418 A157419 * A157421 A157422 A157423

Keyword

nonn

Author

Leroy Quet, Feb 28 2009

Extensions

Extended by Ray Chandler, Jun 19 2009

Status

approved