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%I #7 Jan 10 2018 16:18:27
%S 1,4,9,16,25,36,49,64,81,100,121,145,171,199,229,261,295,331,369,409,
%T 451,496,543,592,643,696,751,808,867,928,991,1056,1124,1194,1266,1340,
%U 1416,1494,1574,1656,1740,1826,1915,2006,2099,2194,2291,2390,2491,2594,2699
%N Index of 10^n within sequence of numbers of form 3^i*10^j.
%H Charles R Greathouse IV, <a href="/A025741/b025741.txt">Table of n, a(n) for n = 1..10000</a>
%o (PARI) a(n)=my(N=1); n+sum(i=2,n, logint(N*=10,3)); \\ _Charles R Greathouse IV_, Jan 10 2018
%o (PARI) first(n)=my(s,N=1/10); vector(n,i, s+=logint(N*=10,3)+1) \\ _Charles R Greathouse IV_, Jan 10 2018
%K nonn,easy
%O 1,2
%A _David W. Wilson_
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