cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A103806 Primes p such that 2p - 33 and 2p + 33 are both primes.

Original entry on oeis.org

2, 5, 7, 13, 19, 23, 37, 47, 53, 67, 73, 103, 137, 157, 163, 173, 193, 227, 233, 277, 313, 347, 353, 397, 443, 457, 613, 733, 863, 877, 983, 1087, 1153, 1213, 1327, 1447, 1493, 1733, 1747, 1787, 1867, 2053, 2063, 2153, 2237, 2377, 2383, 2503, 2557, 2657, 2683
Offset: 1

Views

Author

Zak Seidov, Feb 16 2005

Keywords

Comments

If, e.g., -29 is not prime (Mathematica considers -prime as prime), then the first four terms should be omitted.

Links

Crossrefs

Cf. A103802, A103803, A103804, A103805.

Programs

  • Magma
    [p: p in PrimesUpTo(3000)| IsPrime(2*p+33) and IsPrime(2*p-33) ]; // Vincenzo Librandi, Jan 28 2011
  • Mathematica
    Select[Range[2000], PrimeQ[ # ] && PrimeQ[2# + 33] && PrimeQ[2# - 33] &]
Select[Prime[Range[400]],AllTrue[2#+{33,-33},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Sep 10 2016 *)

Formula

p, 2p-33 and 2p+33 all are primes.

A103807 Primes p such that 2*p-27, 2*p+27, 2*p-33 and 2*p+33 are primes or -1 times primes.

Original entry on oeis.org

2, 5, 7, 23, 37, 103, 313, 457, 733, 863, 2053, 2063, 2917, 4723, 7187, 7817, 8017, 9007, 9473, 9973, 10687, 11527, 11923, 13477, 13883, 15787, 26833, 31477, 34897, 36097, 36353, 36493, 39937, 44417, 46447, 47623, 52103, 53377, 55813, 60737
Offset: 1

Views

Author

Zak Seidov, Feb 16 2005

Keywords

Comments

Intersection of A103805 and A103806.

Crossrefs

Cf. A103805, A103806.

Programs

  • Magma
    [ p: p in PrimesUpTo(61000) | IsPrime(2*p-27) and IsPrime(2*p+27) and IsPrime(2*p-33) and IsPrime(2*p+33) ];
  • Mathematica
    Intersection[Select[Range[100000], PrimeQ[ # ]&&PrimeQ[2#+33]&&PrimeQ[2#-33]&&PrimeQ[ # ]&&PrimeQ[2#+27]&&PrimeQ[2#-27]&]]
okQ[n_]:=Module[{x=2n},And@@PrimeQ[{x-27,x+27,x-33,x+33}]]; Select[Prime[Range[7000]],okQ]  (* Harvey P. Dale, Jan 23 2011 *)
  • PARI
    {forprime(p=2, 61000, if(isprime(abs(2*p-27))&&isprime(2*p+27)&&isprime(abs(2*p-33))&&isprime(2*p+33), print1(p, ", ")))}

Extensions

Definition clarified, comment adjusted, MAGMA and PARI programs added by Klaus Brockhaus, Mar 21 2010
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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