A086390 Composite n such that F(n^2+1)==1 (mod n) where F(k) denotes the k-th Fibonacci number.

4, 9, 10, 12, 20, 24, 27, 28, 36, 48, 50, 60, 63, 72, 76, 84, 96, 99, 100, 108, 110, 120, 140, 144, 161, 168, 180, 192, 196, 204, 216, 220, 228, 231, 240, 250, 252, 276, 288, 300, 323, 324, 336, 341, 351, 360, 364, 369, 377, 384, 408, 420, 432, 451, 456, 480

Offset

1,1

Links

Table of n, a(n) for n=1..56.

Mathematica

Select[Range[500], CompositeQ[#]&&Mod[Fibonacci[#^2+1], #]==1&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 03 2020 *)

Prog

(PARI) isok(n) = !isprime(n) && ((fibonacci(n^2+1) % n) == 1); \\ Michel Marcus, Dec 06 2013

Crossrefs

Cf. A086367.

Subsequence of A086391.

Sequence in context: A243194 A342393 A283320 * A038029 A197039 A020672

Adjacent sequences: A086387 A086388 A086389 * A086391 A086392 A086393

Keyword

nonn

Author

Benoit Cloitre, Sep 06 2003

Status

approved