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.

A281047 Numbers n such that abs(n - 4^k) is prime for k = 1..8.

Original entry on oeis.org

483, 525, 635, 2015, 2043, 3335, 3575, 4275, 10317, 14955, 17855, 22547, 49433, 51695, 52773, 79877, 125807, 132725, 176417, 242073, 314177, 451937, 463517, 590663, 598793, 707817, 795143, 798335, 963815, 994565, 1095465
Offset: 1

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Keywords

Examples

			For n = 483, the primes are {479, 467, 419, 227, 541, 3613, 15901, 65053}.
		

Programs

  • Mathematica
    Select[Range[11*10^5],AllTrue[Abs[#-4^Range[8]],PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 28 2020 *)
  • PARI
    is(n)=for(k=1,8,if(!isprime(abs(n-4^k)), return(0))); 1 \\ Charles R Greathouse IV, Jan 13 2017

Formula

a(n) >> n log^8 n. - Charles R Greathouse IV, Jan 13 2017

Extensions

More terms from Charles R Greathouse IV, Jan 13 2017