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Number of decimal digits of A008559.
2

%I #40 Mar 25 2023 08:19:46

%S 1,2,4,10,31,100,330,1093,3628,12049,40023,132951,441651,1467130,

%T 4873698,16190071,53782249,178660761,593498199,1971558339

%N Number of decimal digits of A008559.

%C a(n+1)/a(n) is approximately log_2(10) = A020862. - _André Engels_, Apr 01 2021

%H Code Golf StackExchange, <a href="https://codegolf.stackexchange.com/questions/253857/length-of-binary-as-base-10-oeis-a242347">Length of Binary as Base 10 [OEIS A242347]</a>, coding challenge started Oct 28 2022.

%F a(n) = A055642(A008559(n)). - _Michel Marcus_, May 11 2014

%e a(3) = 4 because 1010 has 4 decimal digits.

%o (Python)

%o A242347_list, l = [1], 2

%o for _ in range(10):

%o ....l = int(bin(l)[2:])

%o ....A242347_list.append(len(str(l))) # _Chai Wah Wu_, Dec 26 2014

%o (PARI) a242347(n) = {my (k=2, d=digits); while(n--, k=fromdigits(d(k,2))); #d(k)} \\ _Hugo Pfoertner_, Nov 04 2022

%Y Cf. A008559, A055642, A020862.

%K nonn,base,more

%O 1,2

%A _J. Lowell_, May 11 2014

%E a(1), a(18)-a(20) from _Chai Wah Wu_, Dec 26 2014