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A072520 Index of smallest Fibonacci number beginning with the n-th Fibonacci number other than itself. 1
7, 7, 8, 9, 10, 11, 31, 32, 76, 77, 78, 79, 525, 1416, 1417, 1863, 1864, 6004, 6005, 6006, 6007, 6008, 6009, 70009, 70010, 70011, 3853341, 8668488, 11420001, 13139697, 14515454, 15203333, 15547273, 15891213, 15891214, 15891215, 15891216, 63908693, 63908694, 239743481 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..40.

EXAMPLE

a(6) = 11 as the 11th Fibonacci number 89 begins with 8, the 6th Fibonacci number.

MAPLE

N:= 30: # attempt to get a(1)..a(N)

V:= Vector(N):

V[1]:= 7:

count:= 1;

F:= Vector(N, combinat:-fibonacci):

L:= ilog10(F[N]):

tmin:= F[1]:

a:= 1: b:= 1:

for n from 3 to 10^5 while count < N do

  c:= a+b;

  a:= b; b:= c;

  v:= floor(c/10^(max(1, ilog10(c)-L)));

  while v >= tmin do

    j:= ListTools:-BinarySearch(F, v);

    if j > 0 and j <= N and V[j] = 0 then

      count:= count+1;

      V[j]:= n;

      jm:= min(select(t -> V[t]=0, [$1..N]));

      tmin:= F[jm];

    fi;

    v:= floor(v/10);

  od:

od:

seq(V[i], i=1..jm-1); # Robert Israel, Mar 20 2018

CROSSREFS

Cf. A072519.

Sequence in context: A108186 A024818 A076236 * A187179 A110941 A182470

Adjacent sequences:  A072517 A072518 A072519 * A072521 A072522 A072523

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Jul 31 2002

EXTENSIONS

Corrected and extended by Sascha Kurz, Jan 03 2003

a(24)-a(26) from Robert Israel, Mar 20 2018

a(27)-a(40) from Giovanni Resta, Aug 26 2018

STATUS

approved

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Last modified August 6 17:06 EDT 2020. Contains 336255 sequences. (Running on oeis4.)