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5-adic valuation of A007185.
4

%I #12 Aug 01 2012 20:37:49

%S 1,2,4,4,5,6,7,8,9,10,11,12,17,14,15,18,17,18,19,20,21,22,23,24,25,26,

%T 27,29,29,30,33,33,33,35,35,36,37,38,40,40,41,42,43,44,45,46,47,48,50,

%U 51,54,54,54,54,55,56,57,58,59,61,61,63,63,66,66,66,67

%N 5-adic valuation of A007185.

%C a(n) >= n.

%C It appears that the density of n such that a(n) = n is 4/5.

%H Eric M. Schmidt, <a href="/A214880/b214880.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Ar#automorphic">Index entries for sequences related to automorphic numbers</a>

%o (GAP) A214880 := function(max) local result, i; result := [5]; for i in [2..max] do Add(result, result[i-1]^2 mod 10^i); od; result := List(result, x->Valuation(x, 5)); return result; end;

%Y Cf. A214881, A214882, A214883.

%K nonn,base

%O 1,2

%A _Eric M. Schmidt_, Jul 29 2012