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 1-3 of 3 results.

A061421 Primes of the form 2^n+n+1.

Original entry on oeis.org

2, 7, 71, 110427941548649020598956093796432407239217743554726184882600387580788973
Offset: 1

Views

Author

Jason Earls, May 02 2001

Keywords

Comments

Next term is 2^1884+1884+1, with 568 digits and is too large to include. - Emeric Deutsch, May 13 2006
The Wikipedia article "Zeisel number" gives a historical connection to A051015. - Jonathan Sondow, Oct 17 2017

Links

Crossrefs

Cf. A001580, A069539, A052007, A048744, A100357, A100358, A100359.
Cf. A061422.

Programs

  • Maple
    a:=proc(n) if isprime(2^n+n+1)=true then 2^n+n+1 else fi end: seq(a(n),n=0..1000); # Emeric Deutsch, May 13 2006
  • Mathematica
    {ta={{0}}, tb={{0}}};Do[g=n;s=2^n+n+1; If[PrimeQ[s], Print[n];ta=Append[ta, n]; tb=Append[tb, s]], {n, 1, 10000}];{ta, tb, g} (* Labos Elemer, Nov 19 2004 *)

Extensions

Edited by N. J. A. Sloane, May 04 2007

A100359 Numbers k such that 2^k + k + 1 is prime.

Original entry on oeis.org

0, 2, 6, 236, 1884, 51380, 75764
Offset: 1

Views

Author

Labos Elemer, Nov 19 2004

Keywords

Comments

a(8) > 500000. - Robert Price, May 24 2014

Crossrefs

Cf. A001580, A061422, A069539, A052007, A048744, A100357, A100358.

Programs

  • Mathematica
    {ta={{0}}, tb={{0}}};Do[g=n;s=2^n+n+1; If[PrimeQ[s], Print[n];ta=Append[ta, n]; tb=Append[tb, s]], {n, 1, 10000}];{ta, tb, g}
  • PARI
    is(n)=ispseudoprime(2^n+n+1) \\ Charles R Greathouse IV, Feb 20 2017

Formula

a(n) = A061422(n) - 1.

Extensions

a(6) from A061422 Max Alekseyev, Feb 08 2009
a(7) from Giovanni Resta, Mar 19 2014

A100358 Numbers n such that 2^n+n^3+1 is prime.

Original entry on oeis.org

0, 2, 6, 8, 20, 38, 96, 146, 236, 458, 726, 962, 1422, 2864, 3858, 5228, 9822, 21774, 32336, 33336, 43556
Offset: 1

Views

Author

Labos Elemer, Nov 19 2004

Keywords

Comments

a(22) > 200000. - Giovanni Resta, Mar 23 2014
a(22) > 400000. - Robert Price, Sep 01 2014

Crossrefs

Cf. A001580, A069539, A100357.

Programs

  • Maple
    A100358:=n->`if`(isprime(2^n+n^3+1),n,NULL): seq(A100358(n), n=0..10^3); # Wesley Ivan Hurt, Sep 01 2014
  • Mathematica
    {ta={{0}}, tb={{0}}}; Do[g=n;s=2^n+n^3+1;If[PrimeQ[s], Print[n];ta=Append[ta, n];tb=Append[tb, s]], {n, 1, 10000}];{ta, tb, g}
  • PARI
    for(n=1,10^5,if(ispseudoprime(2^n+n^3+1),print1(n,", "))) \\ Derek Orr, Sep 01 2014

Extensions

a(17)-a(21) from Giovanni Resta, Mar 23 2014
Showing 1-3 of 3 results.

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

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