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A108519 a(n) is the smallest natural number m such that (10^n)! - m is prime. 1
11, 271, 6701 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If a(n) is composite then a(n)>10^(2n)+2*10^n. Conjecture: All terms are noncomposite numbers.

LINKS

Table of n, a(n) for n=1..3.

EXAMPLE

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

composite.

MATHEMATICA

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

CROSSREFS

Cf. A108518.

Sequence in context: A285051 A267900 A168147 * A160195 A203240 A062210

Adjacent sequences:  A108516 A108517 A108518 * A108520 A108521 A108522

KEYWORD

more,nonn,bref

AUTHOR

Farideh Firoozbakht, Jul 10 2005

STATUS

approved

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Last modified January 29 16:58 EST 2020. Contains 331347 sequences. (Running on oeis4.)