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 1-6 of 6 results.

A091271 Numbers k such that 4*k^2-11 is a prime.

Original entry on oeis.org

2, 4, 5, 9, 10, 14, 16, 19, 21, 24, 26, 31, 35, 39, 40, 45, 59, 60, 65, 74, 79, 80, 86, 91, 100, 105, 109, 114, 115, 116, 119, 124, 126, 129, 130, 131, 135, 136, 145, 149, 150, 151, 159, 170, 171, 175, 179, 180, 185, 186, 189, 194, 199, 205, 206, 210, 219, 221
Offset: 1

Views

Author

Ray Chandler, Dec 27 2003

Keywords

Crossrefs

A091272 gives primes, A091273 gives prime index.

Programs

  • GAP
    Filtered([2..230],n->IsPrime(4*n^2-11)); # Muniru A Asiru, Jul 10 2018
  • Maple
    select(t -> isprime(4*t^2-11), [$2..1000]); # Robert Israel, Jul 10 2018
  • PARI
    is(n) = ispseudoprime(4*n^2-11) \\ Felix Fröhlich, Jul 10 2018
    

Formula

a(n) = A090696(n)/2.

Extensions

Offset changed by Robert Israel, Jul 10 2018

A091272 Primes of the form n^2 - 11.

Original entry on oeis.org

5, 53, 89, 313, 389, 773, 1013, 1433, 1753, 2293, 2693, 3833, 4889, 6073, 6389, 8089, 13913, 14389, 16889, 21893, 24953, 25589, 29573, 33113, 39989, 44089, 47513, 51973, 52889, 53813, 56633, 61493, 63493, 66553, 67589, 68633, 72889, 73973
Offset: 1

Views

Author

Ray Chandler, Dec 27 2003

Keywords

Crossrefs

Primes arising in A090696 and A091271, A091273 gives prime index.

Programs

A091273 Indices of primes of the form k^2 - 11.

Original entry on oeis.org

3, 16, 24, 65, 77, 137, 170, 227, 273, 341, 392, 532, 654, 792, 833, 1017, 1645, 1686, 1948, 2456, 2757, 2818, 3210, 3550, 4203, 4589, 4898, 5317, 5397, 5482, 5743, 6186, 6364, 6636, 6735, 6822, 7205, 7300, 8198, 8598, 8713, 8820, 9683, 10920, 11040, 11521, 11997
Offset: 1

Views

Author

Ray Chandler, Dec 27 2003

Keywords

Comments

A091272 indexed by A000040.

Crossrefs

Programs

  • Mathematica
    Select[Range[12000],IntegerQ[Sqrt[Prime[#]+11]]&]  (* Harvey P. Dale, Jan 16 2011 *)

Formula

a(n)=j such that A000040(j)=A091272(n).

Extensions

Offset changed to 1 by Jinyuan Wang, Aug 02 2021

A296507 Numbers m such that m^2 - 13 is a prime.

Original entry on oeis.org

4, 6, 12, 18, 24, 30, 36, 54, 72, 84, 90, 96, 102, 114, 120, 138, 168, 186, 198, 204, 210, 216, 228, 240, 276, 294, 318, 330, 354, 360, 372, 378, 402, 414, 438, 444, 456, 480, 498, 504, 588, 600, 612, 618, 630, 636, 666, 678, 690, 714, 720, 726, 732, 738, 762
Offset: 1

Views

Author

Zak Seidov, Dec 13 2017

Keywords

Comments

All terms except 4 are divisible by 6. - Robert Israel, Dec 13 2017

Crossrefs

Programs

  • Maple
    select(n -> isprime(n^2-13), 2*[$2..10^4]); # Robert Israel, Dec 13 2017
  • Mathematica
    Reap[m=4;Do[If[PrimeQ[m^2-13],Sow[m]];m=m+2,{1000}]][[2,1]]
    Select[Range[800],PrimeQ[#^2-13]&] (* Harvey P. Dale, Mar 06 2023 *)
  • PARI
    isok(n) = isprime(n^2-13); \\ Michel Marcus, Dec 14 2017

A186815 Numbers n such that n^2-10 is a prime.

Original entry on oeis.org

9, 21, 27, 39, 51, 69, 81, 87, 99, 117, 129, 147, 153, 171, 177, 183, 207, 219, 249, 261, 309, 333, 351, 363, 387, 393, 399, 429, 441, 447, 459, 471, 477, 483, 519, 537, 561, 597, 609, 621, 633, 639, 651, 663, 687, 711, 717, 723, 741, 753, 777, 807, 849
Offset: 1

Views

Author

Keywords

Examples

			9^2-10=71 prime.
		

Crossrefs

Programs

  • Magma
    [n: n in [1..1000] | IsPrime(n^2-10)]; // Vincenzo Librandi, Jul 10 2016
  • Mathematica
    Select[Range[4,1200],PrimeQ[#^2-10]&]

A309726 Numbers k such that k^2 - 12 is prime.

Original entry on oeis.org

5, 7, 11, 13, 17, 19, 25, 29, 35, 41, 49, 53, 59, 61, 79, 85, 91, 95, 97, 103, 107, 113, 119, 121, 137, 139, 145, 149, 163, 169, 173, 179, 181, 185, 191, 205, 209, 227, 233, 235, 245, 251
Offset: 1

Views

Author

Daniel Starodubtsev, Aug 14 2019

Keywords

Comments

All terms are odd and not divisible by 3.

Examples

			11 is in the sequence because 11^2 - 12 = 109, which is prime.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[5,301,2],PrimeQ[#^2-12]&] (* Harvey P. Dale, Dec 23 2019 *)
  • PARI
    select(n->isprime(n^2-12), [1..1000]) \\ Andrew Howroyd, Aug 14 2019

Formula

If A056927(k) = 12, then k is a term. - A.H.M. Smeets, Aug 15 2019
Showing 1-6 of 6 results.