cp's OEIS Frontend

A217165 a(n) is the least value of k such that the decimal expansion of Fibonacci(k) contains n consecutive identical digits.

%I A217165 #36 Nov 21 2024 14:50:48
%S A217165 0,10,49,66,118,883,2202,6493,62334,135241,353587,1162507,5155873,
%T A217165 7280413,37356153
%N A217165 a(n) is the least value of k such that the decimal expansion of Fibonacci(k) contains n consecutive identical digits.
%C A217165 a(16) > 42000000. - _Paul Geneau de Lamarlière_, Feb 04 2024
%C A217165 a(16) > 10^8. - _Nick Hobson_, Feb 09 2024
%H A217165 Nick Hobson, <a href="/A217165/a217165_1.c.txt">C program</a>
%t A217165 k = 0; Join[{0}, Table[While[d = IntegerDigits[Fibonacci[k]]; ! MemberQ[Partition[Differences[d], n - 1, 1], Table[0, {n - 1}]], k++]; k, {n, 2, 8}]] (* _T. D. Noe_, Oct 02 2012 *)
%o A217165 (Python)
%o A217165 def A217165(n):
%o A217165     if n == 1:
%o A217165         return 0
%o A217165     else:
%o A217165         l, y, x = [str(d)*n for d in range(10)], 0, 1
%o A217165         for m in range(1, 10**9):
%o A217165             s = str(x)
%o A217165             for k in l:
%o A217165                 if k in s:
%o A217165                     return m
%o A217165             y, x = x, y+x
%o A217165         return 'search limit reached'
%o A217165 # _Chai Wah Wu_, Dec 17 2014
%o A217165 (C) // See Links section.
%Y A217165 Cf. A000045, A045875, A215727, A215728, A215729, A215730, A215731.
%K A217165 nonn,base,hard
%O A217165 1,2
%A A217165 _V. Raman_, Sep 27 2012
%E A217165 a(10)-a(11) from _Chai Wah Wu_, Dec 17 2014
%E A217165 a(12)-a(15) from _Paul Geneau de Lamarlière_, Feb 04 2024