A100993 Indices k of Fibonacci numbers F(k) (A000045) that are divisible by k-1.

2, 3, 4, 8, 14, 18, 24, 38, 44, 48, 54, 68, 74, 84, 98, 104, 108, 114, 128, 138, 158, 164, 168, 174, 194, 198, 224, 228, 234, 258, 264, 278, 284, 294, 308, 314, 318, 324, 338, 348, 354, 368, 374, 378, 384, 398, 434, 444, 458, 464, 468, 488, 504, 524, 548, 558

Offset: 1

Author

Ron Knott, Nov 25 2004

Keywords

• nonn

Comments

When k-1 is prime, it is in A003631; when k-1 is composite (such as 323), it is in A069107. - T. D. Noe, Dec 13 2004

Examples

			14 is a term because F(14) = 377 = 13*29 is divisible by 13, one less than its index number 14.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Ron Knott, Mathematical Magic of the Fibonacci Numbers.

Crossrefs

Cf. A000045, A100992, A003631, A023162, A023173, A069104, A069107.

Programs

Mathematica

Select[Range[2, 500], Mod[ Fibonacci[ # ], # - 1] == 0 &] (* Robert G. Wilson v, Nov 26 2004 *)

Formula

a(n) = A069104(n) + 1. - T. D. Noe, Dec 13 2004