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.

A272076 Numbers n such that abs(7*n^2 - 371*n + 4871) is prime.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 56, 59, 61, 63, 65, 67, 68, 72, 73, 74, 75, 76, 77, 78
Offset: 1

Views

Author

Robert Price, Apr 19 2016

Keywords

Examples

			4 is in this sequence since 7*4^2 - 371*4 + 4871 = 112-1484+4871 = 3499 is prime.

Links

Crossrefs

Cf. A050268, A050267, A005846, A007641, A007635, A048988, A050265, A050266.
Cf. A271980, A272074, A272075, A272077.

Programs

  • Mathematica
    Select[Range[0, 100], PrimeQ[7#^2 - 371# + 4871] &]
  • PARI
    lista(nn) = for(n=0, nn, if(ispseudoprime(abs(7*n^2-371*n+4871)), print1(n, ", "))); \\ Altug Alkan, Apr 19 2016

A298078 a(n) = 7*n^2 - 7*n - 43.

Original entry on oeis.org

-43, -29, -1, 41, 97, 167, 251, 349, 461, 587, 727, 881, 1049, 1231, 1427, 1637, 1861, 2099, 2351, 2617, 2897, 3191, 3499, 3821, 4157, 4507, 4871, 5249, 5641, 6047, 6467, 6901, 7349, 7811, 8287, 8777, 9281, 9799, 10331, 10877, 11437, 12011, 12599, 13201, 13817, 14447, 15091, 15749, 16421, 17107
Offset: 1

Views

Author

Charles Kusniec, Jan 11 2018

Keywords

Links

Crossrefs

Cf. A272077.

Programs

  • Mathematica
    Array[7 #^2 - 7 # - 43 &, 48] (* Michael De Vlieger, Jan 11 2018 *)
LinearRecurrence[{3,-3,1},{-43,-29,-1},50] (* Harvey P. Dale, Jul 05 2021 *)
  • PARI
    Vec(-x*(43 - 100*x + 43*x^2) / (1 - x)^3 + O(x^60)) \\ Colin Barker, Jan 14 2018

Formula

From Colin Barker, Jan 14 2018: (Start)
G.f.: -x*(43 - 100*x + 43*x^2) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>3. (End)
E.g.f.: 43 + exp(x)*(-43 + 7*x^2). - Stefano Spezia, Oct 17 2019
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.