login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A215895 Primes p with property that there exists a number D such that p-3D, p-2D, p-D, p+D, p+2D, p+3D are all primes. 2
457, 677, 809, 829, 1039, 1249, 1453, 1459, 1511, 1721, 2083, 2879, 3203, 3499, 3527, 3581, 3919, 4129, 4139, 4157, 4273, 4339, 4549, 5519, 5689, 5711, 5843, 6143, 6329, 6359, 6619, 6803, 6949, 7001, 7013, 7103, 7109, 7211, 7393, 7459, 7477, 7481, 7549, 7673, 7723, 7789 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Conjecture: only 130633 primes are not in the sequence: 2, 3, ..., 94532497.

LINKS

Alois P. Heinz and Lei Zhou, Table of n, a(n) for n = 1..10000 (terms n = 1..2000 from Alois P. Heinz)

EXAMPLE

457 is in the sequence because with D=150: 7, 157, 307, 607, 757, 907 are all primes.

MAPLE

a:= proc(n) option remember; local D, p;

      p:= `if`(n=1, 1, a(n-1));

      do p:= nextprime(p);

        for D to iquo(p, 3) do

          if nops(select(isprime, {(p-k*D)$k=-3..3}))=7

          then return p fi

        od

      od

    end:

seq (a(n), n=1..40);  # Alois P. Heinz, Aug 26 2012

MATHEMATICA

a[n_] := a[n] = Module[{D, p}, p = If[n==1, 1, a[n-1]]; While[True, p = NextPrime[p]; For[D = 1, D <= Quotient[p, 3], D++, If[AllTrue[p - Range[-3, 3] D, PrimeQ], Return [p]]]]];

Array[a, 40] (* Jean-Fran├žois Alcover, Nov 13 2020, after Alois P. Heinz *)

CROSSREFS

Cf. A215642.

Sequence in context: A036271 A061326 A325086 * A142828 A020364 A337847

Adjacent sequences:  A215892 A215893 A215894 * A215896 A215897 A215898

KEYWORD

nonn

AUTHOR

Alex Ratushnyak, Aug 25 2012

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 January 29 03:07 EST 2022. Contains 350672 sequences. (Running on oeis4.)