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 1-7 of 7 results.

A253142 Numbers n such that n + 15 and n^2 + 15 are prime.

Original entry on oeis.org

2, 4, 8, 14, 16, 22, 26, 32, 38, 44, 46, 52, 64, 68, 86, 88, 98, 124, 134, 158, 178, 184, 196, 212, 236, 242, 248, 256, 262, 296, 298, 316, 322, 338, 364, 374, 386, 394, 452, 472, 484, 488, 548, 578, 586, 598, 602, 626, 632, 638, 646, 658, 662, 676, 694, 718, 728, 736, 794, 806, 842, 848, 862
Offset: 1

Views

Author

Zak Seidov, Dec 27 2014

Keywords

Examples

			2 + 15 = 17 and 2^2 + 15 = 19 are both prime, so 2 is in the sequence.
		

Crossrefs

Intersection of A086303 and A121982.

Programs

  • Maple
    select(t -> isprime(t+15) and isprime(t^2+15), [seq(i,i=2..1000,2)]); # Robert Israel, May 07 2019
  • Mathematica
    p = 15; Select[Range[2,1000,2], PrimeQ[p + #^2] && PrimeQ[p + #] &]
    Select[Range[2,1000,2],AllTrue[{#,#^2}+15,PrimeQ]&] (* Harvey P. Dale, Jun 08 2023 *)

A122062 Numbers k such that k^2 + 16 is prime.

Original entry on oeis.org

1, 5, 9, 11, 15, 21, 25, 29, 31, 41, 49, 51, 55, 65, 75, 79, 81, 89, 91, 95, 99, 109, 115, 119, 121, 125, 129, 151, 165, 179, 191, 211, 219, 221, 229, 231, 245, 249, 265, 275, 281, 289, 291, 295, 299, 301, 311, 315, 335, 351, 355, 361, 365, 369, 381, 389, 391
Offset: 1

Views

Author

Parthasarathy Nambi, Sep 14 2006

Keywords

Examples

			If k=99 then k^2 + 16 = 9817 (prime).
		

Crossrefs

Programs

A243450 Primes of the form n^2 + 15.

Original entry on oeis.org

19, 31, 79, 211, 271, 499, 691, 1039, 1171, 1459, 1951, 2131, 2719, 4111, 4639, 5791, 7411, 7759, 9619, 10831, 11251, 15391, 17971, 24979, 29599, 31699, 33871, 38431, 40819, 42451, 44959, 55711, 56659, 58579, 61519, 65551, 68659, 73999, 80671, 87631, 88819
Offset: 1

Views

Author

Vincenzo Librandi, Jun 05 2014

Keywords

Crossrefs

Cf. A121982 (associated n).
Cf. similar sequences listed in A243449.

Programs

  • Magma
    [a: n in [0..1000] | IsPrime(a) where a is n^2+15];
    
  • Mathematica
    Select[Table[n^2 + 15, {n, 0, 1000}], PrimeQ]
  • PARI
    list(lim)=my(v=List(),t); forstep(k=2,sqrtint(lim\1-15),2, if(isprime(t=k^2+15), listput(v,t))); Vec(v) \\ Charles R Greathouse IV, Nov 06 2024

Formula

a(n) >> n^2 log n. - Charles R Greathouse IV, Nov 06 2024

A252783 Numbers n such that n + 15, n^2 + 15, n^3 + 15, n^4 + 15, n^5 + 15 and n^6 + 15 are all prime.

Original entry on oeis.org

2, 4, 10830278, 11409622, 37189336, 41206834, 44438468, 65401492, 67135342, 85329104, 92243452, 110149004, 138651242, 182279216, 205680028, 216904744, 307575212, 309431906, 469311346, 490359076, 527228606, 529432582, 549804952, 572599934, 575037022, 596410214, 599921326, 616509454, 643063226, 679784492, 681657946, 722166524, 736641808, 766101998, 789147538, 824154506, 857134166, 870601984, 878365744, 914746816
Offset: 1

Views

Author

Zak Seidov, Dec 27 2014

Keywords

Examples

			15 + {2, 4, 8, 16, 32, 64} = {17, 19, 23, 31, 47, 79} all primes.
		

Crossrefs

Programs

  • PARI
    isok(n) = isprime(n+15) && isprime(n^2 + 15) && isprime(n^3 + 15) && isprime(n^4 + 15) && isprime(n^5 + 15) && isprime(n^6 + 15); \\ Michel Marcus, Dec 28 2014

A253143 Numbers n such that n + 15, n^2 + 15 and n^3 + 15 are prime.

Original entry on oeis.org

2, 4, 16, 22, 32, 44, 86, 88, 98, 298, 316, 452, 602, 638, 658, 736, 862, 868, 896, 1276, 1358, 1586, 1768, 1996, 2342, 2366, 2444, 2452, 2542, 2788, 2902, 3242, 3448, 3704, 3718, 3998, 4376, 4552, 4928, 5422, 5504, 5566, 5608, 5644, 5728, 5768, 5776, 6664, 6934, 6946, 7708, 7858
Offset: 1

Views

Author

Zak Seidov, Dec 27 2014

Keywords

Examples

			With n=2, n+15 (17), n^2+15 (19) and n^3+15 (23) are all prime.
		

Crossrefs

Subsequence of A253142, A086303 and A121982.

Programs

  • Mathematica
    p = 15; Select[Range[2, 20000, 2], PrimeQ[p + #^3] && PrimeQ[p + #^2] && PrimeQ[p + #] &]
    Select[Range[2,8000,2],AllTrue[#^Range[3]+15,PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Nov 29 2018 *)
  • PARI
    isok(n) = isprime(n+15) && isprime(n^2 + 15) && isprime(n^3 + 15); \\ Michel Marcus, Dec 28 2014

A264790 Numbers k such that k^2 + 17 is prime.

Original entry on oeis.org

0, 6, 24, 60, 66, 78, 90, 108, 144, 162, 174, 186, 234, 252, 294, 300, 318, 330, 336, 342, 372, 396, 420, 438, 456, 462, 468, 498, 528, 594, 636, 648, 654, 672, 720, 750, 798, 804, 834, 858, 888, 924, 930, 966, 984, 990, 1014, 1026, 1032, 1086, 1158, 1194, 1200
Offset: 1

Views

Author

Ilya Gutkovskiy, Nov 25 2015

Keywords

Comments

Primes of the form k^2 + 17 have a representation as a sum of 2 squares because they belong to A002144.
All terms are multiple of 6.

Examples

			a(3) = 24 because 24^2 + 17 = 593, which is prime.
		

Crossrefs

Cf. A228244 (associated primes).
Other sequences of the type "Numbers n such that n^2 + k is prime": A005574 (k=1), A067201 (k=2), A049422 (k=3), A007591 (k=4), A078402 (k=5), A114269 (k=6), A114270 (k=7), A114271 (k=8), A114272 (k=9), A114273 (k=10), A114274 (k=11), A114275 (k=12), A113536 (k=13), A121250 (k=14), A121982 (k=15), A122062 (k=16).

Programs

  • Magma
    [n: n in [0..1200 ] | IsPrime(n^2+17)]; // Vincenzo Librandi, Nov 25 2015
  • Mathematica
    Select[Range[0, 1200], PrimeQ[#^2 + 17] &] (* Michael De Vlieger, Nov 25 2015 *)
  • PARI
    for(n=0, 1e3, if(isprime(n^2+17), print1(n, ", "))) \\ Altug Alkan, Nov 25 2015
    

Formula

A000005(A241847(a(n))) = 2.
A241847(a(n)) = A228244(n).

Extensions

Edited by Bruno Berselli, Nov 26 2015

A253166 Numbers n such that n^k+15, with k=1..7, are all prime.

Original entry on oeis.org

599921326, 1107778868, 2011251698, 3589612642, 4811175086, 6153188512
Offset: 1

Views

Author

Zak Seidov, Dec 28 2014

Keywords

Comments

No term (yet) with n^8 + 15 prime.

Crossrefs

Subsequence of A252783.
Showing 1-7 of 7 results.