login
The OEIS is supported by the many generous donors to the OEIS 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 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A263282 Numbers n such that 6n is in A002822 but n is not. 2
63, 65, 88, 98, 102, 133, 157, 163, 185, 193, 198, 203, 208, 210, 233, 245, 250, 262, 310, 340, 380, 387, 413, 437, 457, 462, 473, 478, 483, 493, 507, 508, 515, 530, 585, 600, 627, 635, 640, 647, 658, 662, 677, 718, 742, 765, 772, 793, 795, 830, 847, 857 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

To use Dinculescu's terminology (see links): non-ranks n such that 6n is a twin-rank.

LINKS

Jason Kimberley, Table of n, a(n) for n = 1..27455 (equivalently, a(n) < 10^6).

A. Dinculescu, On Some Infinite Series Related to the Twin Primes, The Open Mathematics Journal, 5 (2012), 8-14.

A. Dinculescu, The Twin Primes Seen from a Different Perspective, The British Journal of Mathematics & Computer Science, 3 (2013), Issue 4, 691-698.

EXAMPLE

Take n = 63; then 6n = 378 and 36n = 2268; now 379, 2267, and 2269 are prime, but 377 = 13 x 29.

MATHEMATICA

s = Select[Range@ 5184, PrimeQ[6 # - 1] && PrimeQ[6 # + 1] &]; Select[s, IntegerQ[#/6] && ! MemberQ[s, #/6] &]/6 (* Michael De Vlieger, Oct 13 2015, after N. J. A. Sloane at A002822 *)

PROG

(Magma) IsInA2822:=func<n|IsPrime(6*n-1)and IsPrime(6*n+1)>;

[n:n in[1..10^3]|not IsInA2822(n)and IsInA2822(6*n)];

CROSSREFS

Cf. A002822.

Sequence in context: A112816 A296875 A346803 * A295695 A045271 A198294

Adjacent sequences: A263279 A263280 A263281 * A263283 A263284 A263285

KEYWORD

nonn,easy

AUTHOR

Jason Kimberley, Oct 13 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 7 22:27 EST 2022. Contains 358671 sequences. (Running on oeis4.)