This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A067399 Number of divisors of n in OR-numbral arithmetic. 10
 1, 2, 2, 3, 2, 4, 3, 4, 2, 4, 2, 6, 2, 6, 5, 5, 2, 4, 2, 6, 3, 4, 2, 8, 2, 4, 4, 9, 2, 10, 8, 6, 2, 4, 2, 6, 2, 4, 2, 8, 2, 6, 2, 6, 4, 4, 4, 10, 2, 4, 4, 6, 2, 8, 4, 12, 2, 4, 4, 15, 4, 16, 14, 7, 2, 4, 2, 6, 2, 4, 2, 8, 3, 4, 2, 6, 2, 4, 2, 10, 2, 4, 2, 9, 5, 4, 2, 8, 2, 8, 4, 6, 2, 8, 6, 12, 2, 4, 4, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS See A048888 for the definition of OR-numbral arithmetic. The example shows that this sequence is not multiplicative. In other words, number of lunar divisors of n in base 2. REFERENCES A. Frosini and S. Rinaldi, On the Sequence A079500 and Its Combinatorial Interpretations, Journal of Integer Sequences, Vol. 9 (2006), Article 06.3.1. LINKS N. J. A. Sloane, Table of n, a(n) for n = 1..1024 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. EXAMPLE a(15)=5 since [15] has the 5 OR-numbral divisors [1], [3], [5], [7] and [15]. If written as a triangle with rows of lengths 1,2,4,8,16,...: 1, 2, 2, 3, 2, 4, 3, 4, 2, 4, 2, 6, 2, 6, 5, 5, 2, 4, 2, 6, 3, 4, 2, 8, 2, 4, 4, 9, 2, 10, 8, 6, 2, 4, 2, 6, 2, 4, 2, 8, 2, 6, 2, 6, 4, 4, 4, 10, 2, 4, 4, 6, 2, 8, 4, 12, 2, 4, 4, 15, 4, 16, 14, ..., the last terms in each row give A079500(n). The penultimate terms in the rows give 2*A079500(n-1). - N. J. A. Sloane, Mar 05 2011 CROSSREFS A079500 is the subsequence a(2^k-1). - N. J. A. Sloane, Feb 23 2011 Cf. A003986, A007059, A048888, A067138, A067139, A067398, A067400, A067401. See A188548 for the sum of the divisors. Sequence in context: A205000 A066241 A060025 * A106737 A323164 A318881 Adjacent sequences:  A067396 A067397 A067398 * A067400 A067401 A067402 KEYWORD nonn AUTHOR Jens Voß, Jan 23 2002 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 19 15:53 EST 2019. Contains 319307 sequences. (Running on oeis4.)