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 1-5 of 5 results.

A038599 Numbers k such that k^3 - 2 is prime.

Original entry on oeis.org

9, 15, 19, 27, 31, 37, 67, 91, 99, 109, 121, 129, 135, 145, 151, 165, 187, 189, 201, 207, 211, 217, 241, 259, 265, 267, 277, 279, 289, 319, 355, 357, 367, 369, 387, 391, 411, 417, 427, 435, 439, 445, 457, 459, 477, 489, 511, 525, 549, 555, 561, 615, 619, 621
Offset: 1

Views

Author

Keywords

Examples

			15^3 - 2 = 3373 is prime, so 15 is in the sequence.
		

Crossrefs

Programs

Formula

a(n) = (A038600(n)+2)^(1/3). - Zak Seidov, May 10 2016

Extensions

Missed term, 207, and more terms added by Zak Seidov, Mar 14 2009

A178251 Primes p such that p^3 - 2 is prime.

Original entry on oeis.org

19, 31, 37, 67, 109, 151, 211, 241, 277, 367, 439, 457, 619, 691, 727, 787, 859, 967, 1087, 1171, 1471, 1489, 1531, 1579, 1951, 2131, 2287, 2791, 2851, 2971, 3061, 3319, 3511, 3547, 3559, 3739, 4129, 4357, 4447, 4507, 4591, 4651, 4789, 4801, 4831, 4951
Offset: 1

Views

Author

Ulrich Krug (leuchtfeuer37(AT)gmx.de), May 24 2010

Keywords

Examples

			6857 = prime(882) = 19^3 - 2, 19 = prime(8) is 1st term.
29789 = prime(3228) = 31^3 - 2, 31 = prime(11) is 2nd term.
		

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(5000) | IsPrime(p^3-2)]; // Vincenzo Librandi, Nov 17 2010
    
  • Mathematica
    Select[Prime[Range[10000]], PrimeQ[#^3 - 2] &] (* Vincenzo Librandi, Mar 20 2014 *)
  • PARI
    list(lim)=my(v=List()); forprime(p=2,lim, if(isprime(p^3-2), listput(v, p))); Vec(v) \\ Charles R Greathouse IV, Feb 08 2016
  • Sage
    a = list(p for p in primes(10000) if is_prime(p**3-2)) # D. S. McNeil, May 25 2010
    

Extensions

Base tag removed by D. S. McNeil, May 25 2010

A178506 Lesser of a "near cube" twin prime pair (k^3 - 4, k^3 - 2).

Original entry on oeis.org

3371, 8120597, 69426527, 108531329, 176558477, 1207949621, 2379270371, 3477265871, 3560550179, 4227952109, 8012005997, 12665630687, 13060888871, 15832158827, 15945922409, 18337088849, 20279414579, 22354272509, 30283802609, 60559558979, 70496180087, 98035951127
Offset: 1

Views

Author

Ulrich Krug (leuchtfeuer37(AT)gmx.de), May 29 2010

Keywords

Comments

p + 2 = k^3 - 2 is form of "near(est) cube" prime smaller than cube number k^3, as k^3 - 1 = (k-1) * (k^2 + k + 1), only prime for k=2.

Examples

			p = 3371 = prime(475) = 15^3 - 4, (p, p+2) is twin prime pair tp(90), 3371 is the first term.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[10^4]^3 - 4, And @@ PrimeQ[# + {0, 2}] &] (* Amiram Eldar, Dec 25 2019 *)

Extensions

a(13) corrected and more terms from Amiram Eldar, Dec 25 2019

A178507 Numbers n that (n^3 - 4,n^3 - 2) is a twin prime pair.

Original entry on oeis.org

15, 201, 411, 477, 561, 1065, 1335, 1515, 1527, 1617, 2001, 2331, 2355, 2511, 2517, 2637, 2727, 2817, 3117, 3927, 4131, 4611, 4755, 4797, 5121, 5427, 5457, 5787, 6045, 6501, 6675, 7347, 7395, 8637, 9591, 9711, 10071, 10305, 10371, 10377, 10965, 11031
Offset: 1

Views

Author

Ulrich Krug (leuchtfeuer37(AT)gmx.de), May 29 2010

Keywords

Comments

See A178506.
Necessarily n odd multiple of 3, LSD of n is e = 1, 5 or 7.

Examples

			p = 15^3 - 4 = 3371 = prime(475), p+2 = prime(476), 15 is first term.
p = 201^3 - 4 = 8120597 = prime(547310), p+2 = prime(547311), 201 is 2nd term.
p = 15915^3 - 4 = 4031066185871 = prime(i), i = 144036640497, p+2 = prime(i+1), 15915 is another term.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[12000],AllTrue[#^3-{4,2},PrimeQ]&] (* Harvey P. Dale, Jul 28 2024 *)
  • PARI
    is(n) = isprime(n^3-2) && isprime(n^3-4) \\ Michel Marcus, Jul 22 2013

Extensions

Term 6045 added by Michel Marcus, Jul 22 2013

A330438 Numbers k such that k^2-2 and k^3-2 are prime.

Original entry on oeis.org

9, 15, 19, 27, 37, 121, 135, 145, 211, 217, 259, 265, 267, 279, 355, 357, 387, 391, 435, 489, 525, 561, 615, 621, 727, 951, 987, 1029, 1119, 1141, 1177, 1251, 1287, 1357, 1435, 1491, 1561, 1617, 1717, 1785, 1819, 1839, 1875, 1909, 1989, 2001, 2077, 2107, 2211
Offset: 1

Views

Author

K. D. Bajpai, Dec 14 2019

Keywords

Comments

Intersection of A028870 and A038599.

Examples

			a(1) = 9: 9^2 - 2 = 79; 9^3 - 2 = 727; both results are prime.
a(2) = 15: 15^2 - 2 = 223; 15^3 - 2 = 3373; both results are prime.
		

Crossrefs

Programs

  • Magma
    [n : n in [1 .. 100] | IsPrime (n^2 - 2) and IsPrime (n^3 - 2)];
  • Maple
    filter:= k -> isprime(k^2-2) and isprime(k^3-2):
    select(filter, [$2..10000]); # Robert Israel, Dec 24 2019
  • Mathematica
    Select[Range[10000], PrimeQ[#^3 - 2] && PrimeQ[#^2 - 2] &]
Showing 1-5 of 5 results.