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.

A136162 List of prime quadruplets {p, p+2, p+6, p+8}.

Original entry on oeis.org

5, 7, 11, 13, 11, 13, 17, 19, 101, 103, 107, 109, 191, 193, 197, 199, 821, 823, 827, 829, 1481, 1483, 1487, 1489, 1871, 1873, 1877, 1879, 2081, 2083, 2087, 2089, 3251, 3253, 3257, 3259, 3461, 3463, 3467, 3469, 5651, 5653, 5657, 5659, 9431, 9433, 9437
Offset: 1

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Author

Harry J. Smith, Dec 17 2007

Keywords

Comments

{11, 13, 17, 19} is the only prime quadruplet {p, p+2, p+6, p+8} of the form {Q-4, Q-2, Q+2, Q+4} where Q is a product of a pair of twin primes {q, q+2} (for prime q = 3) because numbers Q-2 and Q+4 are for q>3 composites of the form 3*(12*k^2-1) and 3*(12*k^2+1) respectively (k is an integer). Conjecture: {11, 13, 17, 19} is the only prime quadruplet {p, p+2, p+6, p+8} of the form {q*(nextprime(q))-4, q*( nextprime(q))-2, q*( nextprime(q))+2, q*( nextprime(q))+4} where q is a prime (for prime q = 3). - Jaroslav Krizek, Jul 07 2017

Crossrefs

Cf. A007530 (1st quadrisection).

Programs

  • Mathematica
    Map[Prime[Range @@ #] &, MapAt[# + 1 &, SequencePosition[Differences@ Prime@ Range@ 1200, {2, 4, 2}], {All, -1}]] // Flatten (* Michael De Vlieger, Jul 11 2017 *)
  • PARI
    {forprime(p1=0,70000,p2=p1+2;if(!isprime(p2),next;);p3=p1+6;if(!isprime(p3),next;);p4=p1+8;if(!isprime(p4),next;);print1(p1,",",p2,",",p3,",",p4,","))}
    
  • PARI
    q=[0,0,0,0];i=0;forprime(p=5,1e4,(q[i%4+1]=p)==8+q[i++%4+1]&&print1(vecsort(q)","))  \\ M. F. Hasler, Apr 20 2013

Formula

[a(4n-3),a(4n-2),a(4n-1),a(4n)] = A007530(n) + [0,2,6,8], for all n>0. - M. F. Hasler, Apr 20 2013