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.

A300407 Primes of the form 17*2^n + 1.

Original entry on oeis.org

137, 557057, 2281701377, 38280596832649217, 3032901347000164747248857685080177164813336577, 240291200809860268823328460101036918152537809975084178304538443375796289537, 4031417378886400659867047414062478199819447786118941877597755244819503521544011777
Offset: 1

Views

Author

Martin Renner, Mar 05 2018

Keywords

Comments

For the corresponding exponents n see A002259.

Examples

			From _Muniru A Asiru_, Mar 29 2018: (Start)
137 is a member because 17 * 2^3 + 1 = 137 which is a prime.
557057 is a member because 17 * 2^15 + 1 = 557057 which is a prime.
2281701377 is a member because 17 * 2^27 + 1 = 2281701377 which is a prime.
... (End)
		

Crossrefs

Programs

  • GAP
    Filtered(List([1..270],n->17*2^n + 1),IsPrime); # Muniru A Asiru, Mar 06 2018
    
  • Magma
    [a: n in [1..300] | IsPrime(a) where a is 17*2^n + 1]; // Vincenzo Librandi, Mar 07 2018
    
  • Maple
    a:=(n,k)->`if`(isprime(k*2^n+1), k*2^n+1, NULL):
    seq(a(n,17), n=1..267);
  • Mathematica
    Select[Table[17 2^n + 1, {n, 400}], PrimeQ] (* Vincenzo Librandi, Mar 07 2018 *)
  • PARI
    lista(nn) = {for(k=1, nn, if(ispseudoprime(p=17*2^k+1), print1(p, ", ")));} \\ Altug Alkan, Mar 28 2018

A112245 Numbers k such that 65537*2^k+1 is prime.

Original entry on oeis.org

287, 1695, 81359, 512895
Offset: 1

Views

Author

T. D. Noe, Aug 30 2005, Aug 26 2007

Keywords

Comments

Note that 65537=2^16+1 is the largest known Fermat prime. These n yield provable primes. The primes are the smallest numbers in classes 303, 1711 and 81375 of the phi iteration (see A007755).
Jacques Molne found 512895. The corresponding provable prime is the smallest number in class 512911 of the Phi iteration.

Crossrefs

Cf. A002253, A002254, A002259, A053345 (F*2^n+1 is prime, where F is a Fermat prime).

Programs

Showing 1-2 of 2 results.