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.

A162001 Initial members of prime triples (p, p+2, p+6) for which also the sum 3p+8 is prime.

Original entry on oeis.org

5, 11, 17, 41, 101, 311, 347, 641, 857, 1301, 1427, 1481, 2237, 2687, 3461, 3527, 4001, 4787, 8861, 10457, 11171, 11777, 13691, 14627, 19421, 19991, 21017, 21557, 22271, 24917, 25997, 26261, 26681, 26711, 27737, 29021, 31511, 32057, 33347, 35591
Offset: 1

Views

Author

Milton L. Brown (miltbrown(AT)earthlink.net), Jun 24 2009

Keywords

Comments

A subsequence of A022004 (= initial members of prime triples (p, p+2, p+6)). - Emeric Deutsch, Jul 12 2009

Examples

			(5,7,11) => 23 is prime.
		

Crossrefs

Subsequence of A162001.

Programs

  • Maple
    a := proc (n) if isprime(n) = true and isprime(n+2) = true and isprime(n+6) = true and isprime(3*n+8) = true then n else end if end proc: seq(a(n), n = 1 .. 50000); # Emeric Deutsch, Jul 12 2009
  • Mathematica
    Select[Select[Partition[Prime[Range[4000]], 3, 1], Differences[#] == {2, 4} &], PrimeQ[Total[#]] &][[;; , 1]] (* Amiram Eldar, Sep 06 2024 *)
  • PARI
    list(lim)=my(v=List(), p=5, q=7, s); forprime(r=11, lim+6, if(r-p==6 && q-p==2 && isprime(s=3*p+8), listput(v, p)); p=q; q=r); Vec(v) \\ Charles R Greathouse IV, Sep 19 2024

Formula

a(n) == 5 (mod 6). - Hugo Pfoertner, Sep 06 2024
a(n) = (A376013(n) - 8)/3. - Amiram Eldar, Sep 06 2024
a(n) >> n log^4 n. - Charles R Greathouse IV, Sep 19 2024

Extensions

Definition corrected by Emeric Deutsch, Jul 12 2009
Extended by Emeric Deutsch, Jul 12 2009

A377406 Primes which are sums of a prime triple (p, p+4, p+6).

Original entry on oeis.org

31, 211, 1381, 3271, 4999, 6421, 8059, 9769, 10399, 11551, 16249, 20479, 23269, 23629, 27031, 28309, 33349, 35491, 39019, 54139, 63949, 70879, 106591, 109579, 116131, 127219, 130729, 141439, 142969, 150151, 151771, 153589, 163741, 167449, 169591, 195511, 205339, 208489, 210361, 216679, 222601, 224149
Offset: 1

Views

Author

James S. DeArmon, Oct 27 2024

Keywords

Comments

The prime triple herein is restricted to the form (p, p+4, p+6). In number theory, the other form of a prime triple is (p, p+2, p+6).
Equivalently, primes of the form 3*A022005(k) + 10.

Examples

			The first term is 31, the sum of the triple (7, 11, 13).
The second term is 211, the sum of the triple (67, 71, 73).
		

Crossrefs

Subset of A002476.

Programs

  • Maple
    q:= p-> andmap(isprime, (t->[p, t, t-4, t+2])((p+2)/3)):
    select(q, [6*i+1$i=1..50000])[];  # Alois P. Heinz, Nov 13 2024
  • Mathematica
    Select[Total /@ Select[Partition[Prime[Range[7500]], 3, 1], Differences[#] == {4, 2} &], PrimeQ] (* Amiram Eldar, Oct 31 2024 *)
  • Python
    from sympy import isprime
    sums = set()
    for n in range(100000):
        if isprime(n) and isprime(n+4) and isprime(n+6) and isprime(3*n+10):
                sums.add(3*n+10)
    print(sorted(sums))

Formula

a(n) mod 6 = 1.
Showing 1-2 of 2 results.