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Index of 6^n within sequence of numbers of form 4^i*6^j.
1

%I #7 Jan 24 2018 22:34:27

%S 1,3,6,10,16,23,31,41,52,64,77,92,108,125,144,164,185,207,231,256,282,

%T 310,339,369,401,434,468,503,540,578,617,658,700,743,787,833,880,928,

%U 978,1029,1081,1134,1189,1245,1302,1361,1421,1482,1545,1609,1674,1740,1808

%N Index of 6^n within sequence of numbers of form 4^i*6^j.

%o (PARI) a(n)=my(N=1); n+1+sum(i=1, n, logint(N*=6, 4)); \\ _Charles R Greathouse IV_, Jan 16 2018

%o (PARI) first(n)=my(s, N=1/6); vector(n+1, i, s+=logint(N*=6, 4)+1) \\ _Charles R Greathouse IV_, Jan 16 2018

%Y Differs from A025729 at a(65).

%K nonn

%O 1,2

%A _David W. Wilson_