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

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A140775 A number n is included if p + n/p is prime for every prime p that divides n. 3
2, 6, 10, 22, 30, 34, 42, 58, 70, 78, 82, 102, 118, 130, 142, 190, 202, 210, 214, 274, 298, 310, 322, 330, 358, 382, 394, 442, 454, 462, 478, 510, 538, 562, 582, 610, 622, 658, 694, 714, 730, 742, 790, 838, 862, 922, 930, 970, 1002, 1038, 1042, 1110, 1138, 1198 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms of this sequence are even and squarefree.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

The primes dividing 70 are 2, 5, 7. Now, 2 + 70/2 = 37; 5 + 70/5 = 19; 7 + 70/7 = 17. Since 37, 19 and 17 are each prime, then 70 is included in this sequence.

MATHEMATICA

fQ[n_] := Block[{p = First@ Transpose@ FactorInteger@ n}, Union@ PrimeQ[p + n/p] == {True}]; Select[ Range[2, 1221], fQ@# &] - Robert G. Wilson v, May 30 2008

pnpQ[n_]:=AllTrue[#+n/#&/@Transpose[FactorInteger[n]][[1]], PrimeQ]; Select[ Range[2, 1200], pnpQ] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Apr 15 2016 *)

CROSSREFS

Cf. A140776, A140777.

Sequence in context: A112861 A180230 A186296 * A077064 A080715 A034168

Adjacent sequences:  A140772 A140773 A140774 * A140776 A140777 A140778

KEYWORD

nonn

AUTHOR

Leroy Quet, May 29 2008

EXTENSIONS

More terms from Robert G. Wilson v, May 30 2008

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 November 30 08:16 EST 2021. Contains 349419 sequences. (Running on oeis4.)