A088472 -id:A088472 - cp's OEIS frontend

A088469 Number of distinct lunar prime divisors of n.

0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 17, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 15, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 13, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 11, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1

Offset: 1

David Applegate, Nov 11 2003

nonn

a(n) is the number of lunar primes p that are lunar divisors of n. (Multiplicity is not taken into account. Each prime is counted at most once.)

			10 = 9*90 and 90 is prime. 90 is the only prime divisor of 10, so a(10) = 1.

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

Cf. A088471, A088472, A087097.

A088475 Numbers n such that the lunar sum of the distinct lunar prime divisors of n is >= n.

Original entry on oeis.org

10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75

Offset: 1

David Applegate, Nov 11 2003

			The only lunar prime that divides 10 is 90: 90*1 = 10 (cf. A087061, A087062, A087097) and 90 >= 10, so 10 is a member. - _N. J. A. Sloane_, Mar 04 2007, corrected Oct 07 2010.

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.
Tanya Khovanova, Non Recursions
Index entries for sequences related to dismal (or lunar) arithmetic

Complement is A088472, which starts 1, 2, 3, 4, 5, 6, 7, 8, 9, 100, 110, 112, ...

Definition made more precise by Marc LeBrun, Mar 04 2007

cp's OEIS Frontend

A088469 Number of distinct lunar prime divisors of n.

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