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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 (list; graph; refs; listen; history; text; internal format)
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]

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 base-2 version.

Sequence in context: A269667 A171816 A083824 * A104348 A251984 A089186

Adjacent sequences:  A087026 A087027 A087028 * A087030 A087031 A087032

KEYWORD

nonn,base,easy

AUTHOR

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

EXTENSIONS

More terms from David Applegate, Nov 07 2003

STATUS

approved

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Last modified May 27 05:27 EDT 2017. Contains 287189 sequences.