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.

A046848 Primes of form k*2^k+(k-1).

Original entry on oeis.org

2, 67, 389, 32212254749, 584115552289, 1861861819085211933448282832989, 22747455000408352326750293979672813380881340606518608030931171147991
Offset: 1

Views

Author

Keywords

Comments

The next term has 341 digits. - Harvey P. Dale, Apr 15 2017

Crossrefs

Programs

  • Mathematica
    Select[Table[n 2^n+n-1,{n,300}],PrimeQ] (* Harvey P. Dale, Apr 15 2017 *)

Formula

a(n) = A069229(A046849(n)) - 1. - Amiram Eldar, Jul 27 2025

A267094 Primes p such that p*2^p + p + 2 is also prime.

Original entry on oeis.org

3, 5, 11, 17, 31, 43, 139, 173, 3709, 161923
Offset: 1

Views

Author

Emre APARI, Jan 11 2016

Keywords

Comments

Primes p such that A069229(n)+2 is prime. - Michel Marcus, Jan 12 2016
a(11) > 612649. - Robert Price, May 22 2016

Examples

			p=11: ((2^11)*11)+11+2 = 22541 (is prime).
		

Crossrefs

Cf. A069229.

Programs

  • Magma
    [p: p in PrimesUpTo(200) | IsPrime(p*2^p+p+2)]; // Vincenzo Librandi, Jan 19 2016
  • Mathematica
    Select[Prime[Range[4000]], PrimeQ[# 2^# + # + 2] &] (* Vincenzo Librandi, Jan 19 2016 *)
  • PARI
    lista(nn) = forprime(p=2, nn, if(ispseudoprime(p*2^p + p + 2), print1(p, ", "))); \\ Altug Alkan, Jan 12 2016
    

Extensions

a(10) from Giovanni Resta, Apr 10 2016
Showing 1-2 of 2 results.