A072352 a(n) is the largest n-digit Fibonacci number.

8, 89, 987, 6765, 75025, 832040, 9227465, 63245986, 701408733, 7778742049, 86267571272, 956722026041, 6557470319842, 72723460248141, 806515533049393, 8944394323791464, 99194853094755497, 679891637638612258, 7540113804746346429, 83621143489848422977

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..990

Formula

a(n) = A000045(A072353(n)). - Robert Israel, Mar 10 2016

Example

a(3)=987, as 987 is largest 3-digit Fibonacci number.

Maple

fib:= combinat:-fibonacci:
g:= proc(x) local n;
  n:= floor(ln((2*x+1)*sqrt(5)/2)/ln((1+sqrt(5))/2));
  if fib(n) > x then while fib(n) > x do n:= n-1 od
  elif fib(n+1) <= x then while fib(n+1) <= x do n:= n+1 od
  fi;
  fib(n)
end:
seq(g(10^n), n=1..50); # Robert Israel, Mar 10 2016
# second Maple program:
F:= proc(n) option remember; local f;
      f:= `if`(n=1, [1$2], F(n-1));
      do f:= [f[2], f[1]+f[2]];
         if length(f[1])<length(f[2]) then break fi
      od; f
    end:
a:= n-> F(n)[1]:
seq(a(n), n=1..25);  # Alois P. Heinz, Mar 10 2016

Mathematica

Table[k=1; While[Fibonacci@++k<10^n]; Fibonacci[k-1], {n, 20}] (* Giorgos Kalogeropoulos, Jul 06 2021 *)

Prog

(Python)
def A072352_list(n):
    list = []
    x, y = 1, 1
    while len(list) < n:
        if len(str(x)) < len(str(y)):
            list.append(x)
        x, y = y, x + y
    return list
print(A072352_list(20)) # M. Eren Kesim, Jun 28 2021

Crossrefs

Cf. A000045, A072351, A072353.

Sequence in context: A061000 A240457 A319842 * A099100 A208265 A184756

Adjacent sequences: A072349 A072350 A072351 * A072353 A072354 A072355

Keyword

base,nonn

Author

Shyam Sunder Gupta, Jul 17 2002

Status

approved