A098842 Number of n-digit Fibonacci numbers.

7, 5, 5, 4, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 5, 4, 5, 5, 5, 4, 5, 5, 5, 5

Offset: 1

Author

Alex Vinokur (alexvn(AT)barak-online.net), Nov 03 2004

Keywords

• base
• easy
• nonn

Comments

a(1)=7 because the Fibonacci numbers having one digit are the first seven; then the next five have two digits, so a(2)=5.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
• Ron Knott, The Fibonacci Numbers.
• Ron Knott, [Number of digits in Fib(i)] : Calculator.

Crossrefs

Essentially the same as A050815, which is the main entry for this sequence. Cf. A000045, A060384.

Programs

Haskell

a098842 n = a098842_list !! (n-1)
a098842_list = map length $ group a060384_list
-- Reinhard Zumkeller, Mar 09 2013

Mathematica

Join[{7},Rest[Length[#]&/@Split[IntegerLength[Fibonacci[Range[510]]]]]] (* Harvey P. Dale, Jul 19 2020 *)

Extensions

Corrected by Alexandre Wajnberg, Mar 28 2005