

A067139


Irreducible elements in ORnumbral arithmetic.


9



1, 2, 3, 5, 9, 11, 13, 17, 19, 23, 25, 29, 33, 35, 37, 39, 41, 43, 49, 53, 57, 65, 67, 69, 71, 75, 77, 79, 81, 83, 87, 89, 93, 97, 101, 105, 107, 113, 117, 121, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147, 149, 151, 157, 159, 161, 163, 167, 169, 171, 177, 179
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OFFSET

1,2


COMMENTS

Numbers n such that there is no number d in range 1 < d < n with d*k = n for any 1 < k < n, where * is defined in A066376.
See A048888 for the definition of ORnumbral arithmetic. Note that 2 is the only prime element in ORnumbral arithmetic; for all other nonunit irreducibles x there exist numbers a and b not divisible by x such that x is a divisor of a * b.
Numbers n such that A066376(n) = 1.
1 together with primes in lunar arithmetic base 2.  N. J. A. Sloane, Aug 14 2010


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..500
D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic, arXiv:1107.1130 [math.NT], 2011 [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic"  the old name was too depressing]
A. Frosini and S. Rinaldi, On the Sequence A079500 and Its Combinatorial Interpretations, J. Integer Seq., Vol. 9 (2006), Article 06.3.1.
Index entries for sequences related to dismal (or lunar) arithmetic


PROG

(Haskell)
import Data.List (elemIndices)
a067139 n = a067139_list !! (n1)
a067139_list = 1 : map (+ 1) (elemIndices 1 a066376_list)
 Reinhard Zumkeller, Mar 01 2013


CROSSREFS

Cf. A003986, A067138, A048888, A007059.
See A169912 for the number of elements that are n bits long  N. J. A. Sloane, Aug 31 2010. See A171000 for the binary expansions.
Sequence in context: A186776 A191183 A078645 * A014657 A171056 A161514
Adjacent sequences: A067136 A067137 A067138 * A067140 A067141 A067142


KEYWORD

nonn,nice


AUTHOR

Jens Voß, Jan 02 2002


EXTENSIONS

Edited by N. J. A. Sloane at the suggestion of Andrew Plewe and Joshua Zucker, Jun 12 2007


STATUS

approved



