A137574 Fibonacci numbers and their distinct prime divisors having the same number of decimal digits.

2, 3, 5, 8, 13, 21, 89, 233, 1597, 17711, 28657, 46368, 75025, 121393, 514229, 1346269, 165580141, 433494437, 2971215073, 53316291173, 139583862445, 2504730781961, 308061521170129, 806515533049393, 14472334024676221, 99194853094755497, 19740274219868223167

Offset

1,1

Comments

The Fibonacci primes are part of this sequence.

Fibonacci numbers which are semiprimes are also part of the sequence.

Links

Table of n, a(n) for n=1..27.

Ron Knott, Fibonacci Numbers and their prime divisors.

Example

The Fibonacci number 53316291173 and its prime divisors 953 and 55945741 have exactly the same number of decimal digits.

Mathematica

Select[Fibonacci[Range[3, 100]], IntegerLength[#]==Total[IntegerLength/@First/@FactorInteger[#]]&] (* James C. McMahon, May 30 2025 *)

Crossrefs

Cf. A000045, A053409.

Sequence in context: A177246 A067517 A042339 * A041247 A117770 A053412

Adjacent sequences: A137571 A137572 A137573 * A137575 A137576 A137577

Keyword

nonn,base

Author

Parthasarathy Nambi, Apr 25 2008

Extensions

a(21)-a(27) from James C. McMahon, May 30 2025

Status

approved