login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A257146 Primitive non-solvable numbers: elements of A056866 not divisible by any earlier term. 4
60, 168, 1092, 2448, 5616, 6072, 25308, 29120, 32736, 39732, 51888, 74412, 150348, 194472, 285852, 546312, 612468, 1285608, 1934868, 2097024, 2165292, 2588772, 3594432, 3822588, 5848428, 6324552, 7174332, 8487168, 9095592, 10626828, 11332452, 12576732, 14467068, 15331992, 15927348 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A number is solvable if and only if it is a positive multiple of a member of this sequence.

There is 1 member of this sequence up to 10^2, 2 up to 10^3, 6 up to 10^4, 12 up to 10^5, 17 up to 10^6, 29 up to 10^7, 49 up to 10^8, 89 up to 10^9, 169 up to 10^10, 321 up to 10^11, 616 up to 10^12, 1188 up to 10^13, 2351 up to 10^14, 4679 up to 10^15, 9350 up to 10^16, 18866 up to 10^17, 38157 up to 10^18, 77534 up to 10^19, 158048 up to 10^20, 323358 up to 10^21, 663159 up to 10^22, and 1363304 up to 10^23. - Charles R Greathouse IV, Sep 16 2015

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

FORMULA

a(n) >> n^3 log^3 n. - Charles R Greathouse IV, Apr 20 2015

PROG

(PARI) list(lim)={

  my(v=List(), t);

  forprime(p=2, ,

    t=(4^p-1)<<p;

    if(t>lim, break);

    listput(v, t)

  );

  forprime(p=3, ,

    t=3^p*(9^p-1)/2;

    if(t>lim, break);

    listput(v, t)

  );

  forprime(p=7, ,

    t=p*(p^2-1)/2;

    if(t>lim, break);

    listput(v, t)

  );

  forprime(p=3, ,

    t=4^p*(4^p+1)*(2^p-1);

    if(t>lim, break);

    listput(v, t)

  );

  if(lim>=5616, listput(v, 5616));

  v=Set(v);

  for(i=1, #v,

    if(v[i]==60 && i>1, next); \\ see below

    for(j=i+1, #v,

      if(v[j]%v[i]==0, v[j]=60) \\ delete values by setting to v[1]

    )

  );

  Set(v); \\ remove duplicates to combine all 60s

}

CROSSREFS

Cf. A056866.

Sequence in context: A001034 A119630 A216480 * A291549 A259946 A249911

Adjacent sequences:  A257143 A257144 A257145 * A257147 A257148 A257149

KEYWORD

nonn

AUTHOR

Charles R Greathouse IV, Apr 16 2015

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 20 18:26 EDT 2018. Contains 315240 sequences. (Running on oeis4.)