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.

A243451 Primes of the form n^2 + 16.

Original entry on oeis.org

17, 41, 97, 137, 241, 457, 641, 857, 977, 1697, 2417, 2617, 3041, 4241, 5641, 6257, 6577, 7937, 8297, 9041, 9817, 11897, 13241, 14177, 14657, 15641, 16657, 22817, 27241, 32057, 36497, 44537, 47977, 48857, 52457, 53377, 60041, 62017, 70241, 75641, 78977, 83537
Offset: 1

Views

Author

Vincenzo Librandi, Jun 05 2014

Keywords

Comments

Intersection of A241751 and A028916; conjecture: sequence is infinite. - Reinhard Zumkeller, Apr 11 2015

Crossrefs

Cf. A122062 (associated n).
Cf. similar sequences listed in A243449.
Cf. A010051, A241751; subsequence of A028916.
Primes of form n^2+b^4, b fixed: A002496 (b=1), A256775 (b=3), A256776 (b=4), A256777 (b=5), A256834 (b=6), A256835 (b=7), A256836 (b=8), A256837 (b=9), A256838 (b=10), A256839 (b=11), A256840 (b=12), A256841 (b=13).

Programs

  • Haskell
    a243451 n = a243451_list !! (n-1)
    a243451_list = [x | x <- a241751_list, a010051' x == 1]
    -- Reinhard Zumkeller, Apr 11 2015
    
  • Magma
    [a: n in [0..1000] | IsPrime(a) where a is n^2+16];
    
  • Mathematica
    Select[Table[n^2 + 16, {n, 0, 1000}], PrimeQ]
    Select[Range[1,301,2]^2+16,PrimeQ] (* Harvey P. Dale, Nov 05 2015 *)
  • PARI
    list(lim)=if(lim<17,return([])); my(v=List(),t); forstep(n=1,sqrtint(lim\1-16),2, if(isprime(t=n^2+16), listput(v,t))); Vec(v) \\ Charles R Greathouse IV, Aug 18 2017

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
Showing 1-2 of 2 results.