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.

A112855 Numbers n such that (2*n)!/n!+1 is prime.

Original entry on oeis.org

1, 2, 5, 10, 24, 30, 72, 340, 379, 712, 1020, 1647, 3654, 7923
Offset: 1

Views

Author

Hugo Pfoertner, Sep 25 2005

Keywords

Comments

Next term is > 10000.

Crossrefs

Cf. A112856 primes of the form (2*n)!/n!+1, A112853 (2*n)!/n!-1 is prime, A066726 (2*n)!/(n!)^2-1 is prime, A112859 (2*n)!/(n!)^2+1 is prime, A112861 (2*n)!/(2*(n!)^2)-1 is prime, A112863 (2*n)!/(2*(n!)^2)+1 is prime.

Programs

  • Mathematica
    Select[Range[8000],PrimeQ[(2#)!/#!+1]&] (* Harvey P. Dale, Mar 23 2012 *)

A112854 Primes of the form (2*n)!/n!-1.

Original entry on oeis.org

11, 665279, 3497296636753919999, 1960781468160819415703172080467967999999
Offset: 1

Views

Author

Hugo Pfoertner, Sep 25 2005

Keywords

Comments

Next term (2*114)!/114!-1 has 254 decimal digits.

Crossrefs

A112853 gives n such that (2*n)!/n!-1 is prime, A112856 gives primes of the form (2*n)!/n!+1.
Showing 1-2 of 2 results.

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

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