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Number of lunar divisors of n in base 3.
0

%I #15 Aug 06 2014 16:23:20

%S 2,1,4,6,2,2,2,2,6,6,2,12,14,3,4,4,4,3,2,2,4,3,2,4,4,3,8,6,2,12,10,2,

%T 4,2,2,18,10,2,28,34,5,6,7,7,6,2,2,8,7,5,8,8,6,4,2,2,4,2,2,4,2,2,6,2,

%U 2,6,5,2,4,5,2,6,2,2,8,7,2,6,6,6,10,6,2,12,10,2,4,2,2,18,14,3,20,18,2,4,2,2,6,4,4,4,2,2,4,2,2,24,10,2,20,26,4,4,4,4,42,18,2,68

%N Number of lunar divisors of n in base 3.

%H D. Applegate, M. LeBrun and N. J. A. Sloane, <a href="http://arxiv.org/abs/1107.1130">Dismal Arithmetic</a> [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]

%H <a href="/index/Di#dismal">Index entries for sequences related to dismal (or lunar) arithmetic</a>

%e If written as a triangle, with rows of length 2*3^i:

%e 2, 1,

%e 4, 6, 2, 2, 2, 2,

%e 6, 6, 2, 12, 14, 3, 4, 4, 4, 3, 2, 2, 4, 3, 2, 4, 4, 3,

%e 8, 6, 2, 12, 10, 2, 4, 2, 2, 18, 10, 2, 28, 34, 5, 6, 7, 7, 6, 2, 2, 8, 7, 5, 8, 8, 6, 4, 2, 2, 4, 2, 2, 4, 2, 2, 6, 2, 2, 6, 5, 2, 4, 5, 2, 6, 2, 2, 8, 7, 2, 6, 6, 6,

%e 10, 6, 2, 12, 10, 2, 4, 2, 2, 18, 14, 3, 20, 18, 2, 4, 2, 2, 6, 4, 4, 4, 2, 2, 4, 2, 2, 24, 10, 2, 20, 26, 4, 4, 4, 4, 42, 18, 2, 6, ...

%Y Cf. A007089. This is the base-3 analog of A067399.

%K base,nonn

%O 1,1

%A _N. J. A. Sloane_, Mar 05 2011