

A087029


Number of lunar divisors of n (unbounded version).


11



9, 8, 7, 6, 5, 4, 3, 2, 1, 18, 90, 16, 14, 12, 10, 8, 6, 4, 2, 16, 16, 72, 14, 12, 10, 8, 6, 4, 2, 14, 14, 14, 56, 12, 10, 8, 6, 4, 2, 12, 12, 12, 12, 42, 10, 8, 6, 4, 2, 10, 10, 10, 10, 10, 30, 8, 6, 4, 2, 8, 8, 8, 8, 8, 8, 20, 6, 4, 2, 6, 6, 6, 6, 6, 6, 6, 12, 4, 2, 4, 4, 4, 4
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OFFSET

1,1


COMMENTS

Number of d, 1 <= d <= infinity, such that there exists an e, 1 <= e <= infinity, with d*e = n, where * is lunar multiplication.


LINKS

D. Applegate, Table of n, a(n) for n = 1..100000
D. Applegate, C program for lunar arithmetic and number theory [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic"  the old name was too depressing]
D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic"  the old name was too depressing]
D. Applegate, M. LeBrun, N. J. A. Sloane, Dismal Arithmetic, J. Int. Seq. 14 (2011) # 11.9.8.
Index entries for sequences related to dismal (or lunar) arithmetic


EXAMPLE

The 18 divisors of 10 are 1, 2, ..., 9, 10, 20, 30, ..., 90, so a(10) = 18.


MAPLE

(Uses programs from A087062. This crude program is valid for n <= 99.) dd2 := proc(n) local t1, t2, i, j; t1 := []; for i from 1 to 99 do for j from i to 99 do if dmul(i, j) = n then t1 := [op(t1), i, j]; fi; od; od; t1 := convert(t1, set); t2 := sort(convert(t1, list)); nops(t2); end;


CROSSREFS

Cf. A087028, A087083, A186443, A186510. See A189506 for the actual divisors.
See A067399 for the base2 version.
Sequence in context: A269667 A171816 A083824 * A104348 A251984 A089186
Adjacent sequences: A087026 A087027 A087028 * A087030 A087031 A087032


KEYWORD

nonn,base,easy,changed


AUTHOR

Marc LeBrun and N. J. A. Sloane, Oct 19 2003


EXTENSIONS

More terms from David Applegate, Nov 07 2003


STATUS

approved



