%I
%S 1,1,2,3,4,5,6,6,7,8,9,10,11,11,12,13,14,15,16,17,17,18,19,20,21,22,
%T 22,23,24,25,26,27,28,28,29,30,31,32,33,33,34,35,36,37,38,39,39,40,41,
%U 42,43,44,44,45,46,47,48,49,50,50,51,52,53,54,55,55,56,57
%N Number of digits in 7^n.
%F a(n) = A055642(A000420(n)) = A055642(7^n) = floor(log10(10*(7^n))). [Jonathan Vos Post, Mar 23 2012]
%t Table[Length[IntegerDigits[7^n]], {n, 0, 100}] (* _T. D. Noe_, Mar 20 2012 *)
%o (MAGMA) [#Intseq(7^n): n in [0..67]]; // Bruno Berselli, Mar 22 2012
%Y Cf. A000420, A034887, A034888, A210434A210436.
%K nonn,base,easy
%O 0,3
%A _Luc ComeauMontasse_, Mar 16 2012
