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!)
A080195 11-smooth numbers which are not 7-smooth. 3
11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 121, 132, 154, 165, 176, 198, 220, 231, 242, 264, 275, 297, 308, 330, 352, 363, 385, 396, 440, 462, 484, 495, 528, 539, 550, 594, 605, 616, 660, 693, 704, 726, 770, 792, 825, 847, 880, 891, 924, 968, 990, 1056, 1078, 1089 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers of the form 2^r*3^s*5^t*7^u*11^v with r, s, t, u >= 0, v > 0.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = 11 * A051038(n). - David A. Corneth, May 27 2017

EXAMPLE

33 = 3*11 is a term but 35 = 5*7 is not.

MAPLE

N:= 10^6; # to get all terms <= N

A:= NULL;

for v from 1 to floor(log[11](N)) do

   V:= 11^v;

   for u from 0 to floor(log[7](N/V)) do

      U:= 7^u*V;

      for t from 0 to floor(log[5](N/U)) do

        T:= 5^t*U;

        for s from 0 to floor(log[3](N/T)) do

          S:= 3^s*T;

          for r from 0 to floor(log[2](N/S)) do

             A:= A, 2^r*S

          od

         od

       od

    od

od:

{A}; # Robert Israel, May 28 2014

PROG

(PARI) {m=1100; z=[]; for(r=0, floor(log(m)/log(2)), a=2^r; for(s=0, floor(log(m/a)/log(3)), b=a*3^s; for(t=0, floor(log(m/b)/log(5)), c=b*5^t; for(u=0, floor(log(m/c)/log(7)), d=c*7^u; for(v=1, floor(log(m/d)/log(11)), z=concat(z, d*11^v)))))); z=vecsort(z); for(i=1, length(z), print1(z[i], ", "))}

CROSSREFS

Cf. A051038, A002473.

Sequence in context: A059632 A008593 A135499 * A004920 A136613 A113585

Adjacent sequences:  A080192 A080193 A080194 * A080196 A080197 A080198

KEYWORD

easy,nonn

AUTHOR

Klaus Brockhaus, Feb 10 2003

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 September 21 14:54 EDT 2020. Contains 337272 sequences. (Running on oeis4.)