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a(n) is the first digit to appear n times in succession in a power of 3.
14

%I #25 Nov 09 2024 14:48:15

%S 1,7,8,5,5,8,2,1,2,2,2,4,5,8,2,4,4

%N a(n) is the first digit to appear n times in succession in a power of 3.

%o (Python)

%o def A215733(n):

%o l, x = [str(d)*n for d in range(10)], 1

%o for m in range(10**9):

%o s = str(x)

%o for k in range(10):

%o if l[k] in s:

%o return k

%o x *= 3

%o return 'search limit reached'

%o # _Chai Wah Wu_, Dec 17 2014

%Y Cf. A215727, A045875, A215732.

%K nonn,base,more

%O 1,2

%A _V. Raman_, Aug 22 2012

%E a(12) from _Chai Wah Wu_, Dec 17 2014

%E a(13)-a(14) from _Giovanni Resta_, Apr 20 2016

%E a(15) from _Bert Dobbelaere_, Mar 04 2019

%E a(16)-a(17) from _Bert Dobbelaere_, Mar 20 2019