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.

A252862 Initial members of prime sextuples (n, n+2, n+6, n+8, n+18, n+20).

Original entry on oeis.org

11, 18041, 97841, 165701, 392261, 663581, 1002341, 1068701, 1155611, 1329701, 1592861, 1678751, 1718861, 1748471, 2159231, 2168651, 2177501, 2458661, 2596661, 3215741, 3295541, 3416051, 3919241, 4353311, 5168921, 5201291, 5205461, 6404771
Offset: 1

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Author

Karl V. Keller, Jr., Dec 23 2014

Keywords

Comments

This sequence is prime n, where there exist three twin prime pairs of (n,n+2), (n+6,n+8) and (n+18,n+20).
This is a subsequence of A132232 (Primes congruent to 11 mod 30 ).
Also, this is a subsequence of A128467 (30k+11).

Examples

			For n = 18041, the numbers, 18041, 18043, 18047, 18049, 18059, 18061, are primes.
		

Crossrefs

Cf. A077800 (twin primes), A030430 (primes,10*n+1), A132232, A128467, A172456.

Programs

  • Mathematica
    Select[Prime[Range[2500]], Union[PrimeQ[{#, # + 2, # + 6, # + 8, # + 18, # + 20}]] = {True} &] (* Alonso del Arte, Dec 23 2014 *)
    Select[Prime[Range[450000]],AllTrue[#+{2,6,8,18,20},PrimeQ]&] (* Harvey P. Dale, Jun 11 2023 *)
  • PARI
    forprime(p=1,10^7,if(isprime(p+2) && isprime(p+6) && isprime(p+8) && isprime(p+18) && isprime(p+20), print1(p,", "))) \\ Derek Orr, Dec 31 2014
  • Python
    from sympy import isprime
    for n in range(1,10000001,2):
      if isprime(n) and isprime(n+2) and isprime(n+6) and isprime(n+8) and isprime(n+18) and isprime(n+20): print(n,end=', ')
    

A382970 Numbers k such that {k, k+2, k+6, k+8, k+90, k+92, k+96, k+98} are all prime.

Original entry on oeis.org

11, 101, 15641, 3512981, 6655541, 20769311, 26919791, 41487071, 71541641, 160471601, 189425981, 236531921, 338030591, 409952351, 423685721, 431343461, 518137091, 543062621, 588273221, 637272191, 639387311, 647851571, 705497951, 726391571, 843404201, 895161341, 958438751, 960813851, 964812461, 985123961
Offset: 1

Views

Author

David Mellinger, Apr 10 2025

Keywords

Comments

Each term is the initial member of two prime quadruples (A007530) with a difference of 90, the second-smallest possible distance between prime quadruples (A059925 has the smallest).

Examples

			a(1) corresponds to the set of primes {11,13,17,19,101,103,107,109} and a(2) corresponds to {101,103,107,109,191,193,197,199}.
		

Crossrefs

Subsequence of A128467.

Programs

  • MATLAB
    find(corr([1 1 0 1 1 zeros(1,40) 1 1 0 1 1],isprime(3:2:1e8))>7.5)*2-97

Formula

a(n) == 11 (mod 30).
Showing 1-2 of 2 results.