OFFSET
0,2
COMMENTS
Since 19 is the smallest lunar prime, this is a kind of lunar analog of the even numbers.
As the b-file shows, this sequence is not monotonic and contains repetitions.
LINKS
N. J. A. Sloane, Table of n, a(n) for n = 0..10000
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]
FORMULA
For a two-digit number n, the lunar product 19*n is obtained by putting a 1 in front of n.
EXAMPLE
19 * 3 = 13, so 13 is a member. 1109 has just two divisors, 9 and 109, so 1109 is not a member.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Emilie Hogan, Dennis Hou, Kellen Myers and N. J. A. Sloane, Apr 09 2010
EXTENSIONS
Entry revised by N. J. A. Sloane, May 28 2011, to correct errors in some of the comments
STATUS
approved