A057218 - OEIS

A057218

a(n) = least prime of the form n*k! + 1.

2, 3, 7, 5, 11, 7, 43, 17, 19, 11, 23, 13, 79, 29, 31, 17, 103, 19, 457, 41, 43, 23, 47, 577, 151, 53, 163, 29, 59, 31, 156241, 193, 67, 24481, 71, 37, 223, 229, 79, 41, 83, 43, 1033, 89, 271, 47, 283, 97, 5881, 101, 103, 53, 107, 109, 331, 113, 6841, 59, 2355091201, 61

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OFFSET

1,1

COMMENTS

First prime in the sequence n + 1, 2n + 1, 6n + 1, 24n + 1, 120n + 1, ...

If p is a prime then a(p-1) = p.

LINKS

Table of n, a(n) for n=1..60.

EXAMPLE

n=275, for k=1,..,24 {1+275*k!}={276,551,.......,170623310476640845824000001} and a(275)=170623310476640845824000001, the prime generated by A057217(275)=24 as 1+275*24!

PROG

(PARI) a(n) = k = 1; while (!isprime(p=1+n*k!), k++); p; \\ Michel Marcus, Feb 20 2016

CROSSREFS

Primes arising in A057217.

Sequence in context: A087386 A110359 A092977 * A087387 A275205 A327093

Adjacent sequences: A057215 A057216 A057217 * A057219 A057220 A057221

KEYWORD

nonn

AUTHOR

Labos Elemer, Sep 27 2000

EXTENSIONS

More terms from Mark Hudson (mrmarkhudson(AT)hotmail.com), Aug 12 2004

STATUS

approved