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 1-4 of 4 results.

A174363 Primes p such that 2*p^3 -+ 3 are also prime.

Original entry on oeis.org

2, 13, 1223, 2357, 4013, 4027, 4507, 5903, 8713, 9623, 10663, 11717, 12757, 12983, 13883, 15877, 16103, 16787, 16823, 16883, 18097, 22697, 23357, 24677, 26107, 27953, 28603, 30313, 31327, 34147, 35617, 35933, 41183, 44893, 46687, 46817, 48247, 50417, 52963, 54083
Offset: 1

Views

Author

Vincenzo Librandi, Mar 17 2010

Keywords

Comments

Intersection of A153507 and A243630. - Felix Fröhlich, Nov 27 2019

Examples

			For p=2, 2*2^3 -+ 3 = (13, 19), both prime, so 2 is a term of the sequence.
For p=13, 2*13^3 -+ 3 = (4391, 4397), both prime, so 13 is a term of the sequence.
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(100000)|IsPrime(2*p^3-3) and IsPrime(2*p^3+3)]
    
  • Maple
    select(p -> andmap(isprime, [p, 2*p^3+3, 2*p^3-3]), [seq(p, p=1.. 10^5)]); # K. D. Bajpai, Nov 28 2019
  • Mathematica
    Select[Prime[Range[5000]],And@@PrimeQ[2 #^3+{3,-3}]&] (* Harvey P. Dale, Jan 25 2013 *)
  • PARI
    forprime(p=1, 55000, if(ispseudoprime(2*p^3-3) && ispseudoprime(2*p^3+3), print1(p, ", "))) \\ Felix Fröhlich, Nov 27 2019

A243595 Primes p such that 3 + 2*p^2 is also prime.

Original entry on oeis.org

2, 5, 7, 23, 37, 43, 47, 83, 103, 107, 113, 127, 197, 373, 433, 463, 467, 523, 547, 587, 593, 617, 733, 743, 797, 863, 877, 887, 953, 1097, 1163, 1213, 1297, 1427, 1493, 1567, 1583, 1657, 1667, 1693, 1783, 1877, 1987, 2053, 2063, 2087, 2207, 2357, 2557, 2753
Offset: 1

Views

Author

Zak Seidov, Jun 07 2014

Keywords

Comments

Corresponding primes 3 + 2*p^2 are congruent to 5 modulo 6.

Examples

			2 is in the sequence because 3+2*2^2 = 11 is prime; also, for the comment, 11 = 6+5.
5 is in the sequence because 3+2*5^2 = 53 is prime, also 53 = 6*8+5.
7 is in the sequence because 3+2*7^2 = 101 is prime, also 101 = 6*16+5.
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(4000) | IsPrime(3+2*p^2)]; // Bruno Berselli, Jun 07 2014
    
  • Mathematica
    Select[Prime[Range[500]], PrimeQ[3 + 2 #^2] &] (* Bruno Berselli, Jun 07 2014 *)
  • PARI
    s=[]; forprime(p=2, 4000, if(isprime(3+2*p^2), s=concat(s, p))); s \\ Colin Barker, Jun 07 2014
    
  • Sage
    [p for p in primes(4000) if is_prime(3+2*p^2)] # Bruno Berselli, Jun 07 2014

A243630 Primes p such that 2*p^3 - 3 is also prime.

Original entry on oeis.org

2, 7, 11, 13, 47, 101, 107, 151, 163, 167, 251, 257, 401, 443, 467, 521, 571, 641, 653, 673, 797, 907, 911, 971, 983, 997, 1013, 1151, 1153, 1181, 1187, 1223, 1231, 1277, 1291, 1303, 1361, 1433, 1481, 1511, 1597, 1637, 1723, 1741, 1811, 1951, 2027, 2081, 2083, 2141, 2287, 2311
Offset: 1

Views

Author

Vincenzo Librandi, Jun 08 2014

Keywords

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(2500) | IsPrime(2*p^3 - 3)];
  • Mathematica
    Select[Prime[Range[2500]], PrimeQ[2 #^3 - 3] &]

A252042 Primes p such that 2*p^3 + 1 and 2*p^3 + 3 are also primes.

Original entry on oeis.org

2, 29, 1709, 5849, 6857, 6959, 8999, 10139, 11909, 13127, 13877, 15077, 15749, 17657, 19457, 23357, 23399, 26729, 27407, 27479, 28349, 30047, 31907, 32957, 39569, 46559, 46589, 46817, 50417, 58757, 59219, 60737, 62207, 62687, 62819, 66947, 70589, 71237, 74699
Offset: 1

Views

Author

K. D. Bajpai, Dec 13 2014

Keywords

Examples

			a(2) = 29 is prime: 2*29^3 + 1 = 48779 and 2*29^3 + 3 = 48781 are both primes.
a(3) = 1709 is prime: 2*1709^3 + 1 = 9982887659 and 2*1709^3 + 3 = 9982887661 are both primes.
		

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[10000]], And[PrimeQ[2*#^3 + 1], PrimeQ[2*#^3 + 3]] &]
    Select[Prime[Range[7500]],AllTrue[2#^3+{1,3},PrimeQ]&] (* Harvey P. Dale, Apr 03 2023 *)
  • PARI
    s=[]; forprime(p=2, 10^5, if(isprime(2*p^3 + 1) && isprime(2*p^3 + 3), s=concat(s, p))); s
Showing 1-4 of 4 results.