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A214434 Composite n such that n divides Fibonacci(n + 1) or Fibonacci(n - 1) and 2^(n - 1) mod n = 1. 1
6601, 13981, 30889, 68101, 219781, 252601, 332949, 399001, 512461, 642001, 721801, 722261, 741751, 852841, 873181, 1024651, 1141141, 1193221, 1207361, 1533601, 1690501, 1735841, 1857241, 1909001 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Pseudoprimes to a criterion for primality which tests that

1. n divides Fibonacci(n + 1) or Fibonacci(n - 1). (see A182554, A081264)

2. 2^(n - 1) mod n = 1  (see A001567)

All terms appear to be 1 or -1 mod 5.

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..671 (terms < 4*10^9)

FORMULA

Intersection of A182554 and A001567.

EXAMPLE

6601 is in the sequence because the 6600th Fibonacci number is divisible by 6601 and 2^6600 = 1 mod 6601.

MAPLE

with(combinat):f:= n-> fibonacci(n): for n from 1 to 2000000 do if(f(n+1) mod n = 0 or f(n-1) mod n = 0) and 2^(n-1) mod n = 1 and not isprime(n) then print(n) fi od;

CROSSREFS

Cf. A182554, A081264, A001567.

Sequence in context: A186563 A252637 A164971 * A317247 A290281 A178213

Adjacent sequences:  A214431 A214432 A214433 * A214435 A214436 A214437

KEYWORD

nonn

AUTHOR

Gary Detlefs, Jul 17 2012

STATUS

approved

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Last modified March 26 10:18 EDT 2019. Contains 321491 sequences. (Running on oeis4.)