login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A275200 Numbers having fewer distinct prime factors of form 6*k+1 than of the form 6*k+5. 3
5, 10, 11, 15, 17, 20, 22, 23, 25, 29, 30, 33, 34, 40, 41, 44, 45, 46, 47, 50, 51, 53, 55, 58, 59, 60, 66, 68, 69, 71, 75, 80, 82, 83, 85, 87, 88, 89, 90, 92, 94, 99, 100, 101, 102, 106, 107, 110, 113, 115, 116, 118, 120, 121, 123, 125, 131, 132, 135, 136 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Clark Kimberling, Table of n, a(n) for n = 1..1000

EXAMPLE

30 = 2^1 3^1 5^1 , so that the number of distinct primes 6*k+1 is 0 and the number of distinct primes 6*k + 5 is 1.

MATHEMATICA

g[n_] := Map[First, FactorInteger[n]];

p1 = Select[Prime[Range[200]], Mod[#, 6] == 1 &];

p2 = Select[Prime[Range[200]], Mod[#, 6] == 5 &];

q1[n_] := Length[Intersection[g[n], p1]]

q2[n_] := Length[Intersection[g[n], p2]]

Select[Range[200], q1[#] == q2[#] &] (* A275199 *)

Select[Range[200], q1[#] < q2[#] &]  (* A275200 *)

Select[Range[200], q1[#] > q2[#] &]  (* A275201 *)

CROSSREFS

Cf. A275199, A275201.

Sequence in context: A296699 A297132 A136823 * A225838 A036788 A136811

Adjacent sequences:  A275197 A275198 A275199 * A275201 A275202 A275203

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Jul 20 2016

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 28 01:34 EDT 2020. Contains 334671 sequences. (Running on oeis4.)