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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.

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A108519 a(n) is the smallest natural number m such that (10^n)! - m is prime.

Original entry on oeis.org

11, 271, 6701, 40471
Offset: 1

Views

Author

Farideh Firoozbakht, Jul 10 2005

Keywords

Comments

If a(n) is composite then a(n)>10^(2n)+2*10^n. Conjecture: All terms are noncomposite numbers.
(10^4)!-40471 is a probable prime. - Jason Yuen, May 20 2024

Examples

			a(3)=6701 because (10^3)!-6701 is prime and for 0<m<6701 1000!-m is
composite.

Crossrefs

Cf. A108518, A033933.

Programs

  • Mathematica
    a[n_] := (For[m = 1, ! PrimeQ[(10^n)! - m], m++ ]; m); Do[Print[a[n]], {n, 3}]

Formula

a(n) = A033933(10^n). - Jason Yuen, May 20 2024

Extensions

a(4) from Jason Yuen, May 20 2024
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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