A094410 Numbers k that divide Fibonacci(k-1) but do not divide Fibonacci(k) - 1.

442, 1891, 6601, 8149, 13981, 17119, 17711, 30889, 40501, 52701, 68101, 78409, 88601, 88831, 115231, 138601, 145351, 150121, 153781, 191351, 199801, 218791, 265881, 266071, 316561, 332949, 342271, 348517, 407353, 453151, 456301, 464101

Offset: 1

Author

Eric Rowland, May 01 2004

Keywords

• nonn

Links

• Giovanni Resta, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000045, A069106, A094394, A094409.

Programs

Mathematica

Select[Range[50000], ! Mod[Fibonacci[ # ] - 1, # ] == 0 && Mod[Fibonacci[ # - 1], # ] == 0 &]

PARI

fibmod(n,m)=(Mod([0,1;1,1],m)^n*[0;1])[1,1]
is(n)=fibmod(n-1,n)==0 && fibmod(n,n)!=1 \\ Charles R Greathouse IV, Nov 04 2016

Extensions

More terms from David Wasserman, May 08 2007