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 1-3 of 3 results.

A224626 Primes p such that q=2*p^3-1, r=2*p*q^2-1, and s=2*p*r^2-1 are all prime.

Original entry on oeis.org

27361, 65731, 167623, 424093, 1559449, 2389693, 3880633, 4683661, 5755921, 5780881, 6124411, 6840643, 7802959, 7822879, 7917769, 8876719, 9488683, 9640321, 9966139, 10392073, 10865083, 10988743, 12363991, 12457681, 12756253, 13471561, 14437561, 14508709, 14550331, 14839711, 15366223, 16574143
Offset: 1

Views

Author

Pierre CAMI, Apr 12 2013

Keywords

Comments

A prime p here is prime p(n) when A224611(n) = 1.
A subsequence of A224614. - M. F. Hasler, Apr 22 2013

Crossrefs

Programs

  • Mathematica
    Reap[ For[p = 2, p < 2*10^7, p = NextPrime[p], If[PrimeQ[q = 2*p^3 - 1] && PrimeQ[r = 2*p*q^2 - 1] && PrimeQ[2*p*r^2 - 1], Print[p]; Sow[p]] ]][[2, 1]] (* Jean-François Alcover, Apr 22 2013 *)
    apQ[n_]:=Module[{q=2n^3-1,r},r=2n q^2-1;And@@PrimeQ[{q,r,2n r^2-1}]]; Select[ Prime[Range[1100000]],apQ] (* Harvey P. Dale, Nov 24 2013 *)

A224990 Primes p such that q = 2*p^2 - 1 and 2*p*q - 1 are also prime.

Original entry on oeis.org

3, 13, 157, 181, 739, 829, 937, 1009, 1093, 1483, 1621, 1879, 2311, 2503, 2647, 2719, 3079, 4969, 4999, 5209, 5431, 5569, 6163, 6961, 8161, 8329, 9349, 9631, 10399, 10459, 10531, 10657, 11131, 11953, 13063, 18523, 20149, 20731, 21391, 21589, 26317, 27481, 28111, 28351, 29023
Offset: 1

Views

Author

M. F. Hasler, Apr 22 2013

Keywords

Comments

Subsequence of A106483, and more elementary version of A224614.

Programs

  • Mathematica
    Select[Prime[Range[10000]], PrimeQ[2#^2 - 1] && PrimeQ[4#^3 - 2# - 1] &] (* Alonso del Arte, Apr 22 2013 *)
  • PARI
    forprime(p=1,3e4,isprime(r=2*p^2-1)&&isprime(2*p*r-1)&&print1(p","))

A224627 Prime numbers p such that 2*p^3-1, 2*p*q^2-1, 2*p*r^2-1, and 2*p*s^2-1 are prime numbers.

Original entry on oeis.org

19460899, 86276401, 87980803, 167646631, 300722029, 343507111, 479516311, 906597943, 998757829, 1031308249, 1112697199, 1311383431, 1962194053
Offset: 1

Views

Author

Pierre CAMI, Apr 12 2013

Keywords

Comments

Subsequence of A224612, p = prime(n) when A224612(n)=1.

Crossrefs

Programs

  • Mathematica
    Reap[ For[p = 2, p < 2*10^9, p = NextPrime[p], If[PrimeQ[q = 2*p^3 - 1] && PrimeQ[r = 2*p*q^2 - 1] && PrimeQ[s = 2*p*r^2 - 1] && PrimeQ[2*p*s^2 - 1], Print[p]; Sow[p]] ]][[2, 1]] (* Jean-François Alcover, Apr 22 2013 *)

Extensions

More terms from Jean-François Alcover, Apr 22 2013
Showing 1-3 of 3 results.