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A108518 a(n) is the smallest natural number m such that (10^n)! + m is prime. 1
1, 11, 229, 1283 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
If a(n) is composite then a(n)>10^(2n)+2*10^n. Conjecture: All terms are noncomposite numbers.
LINKS
EXAMPLE
a(3)=1283 because (10^3)!+1283 is prime and for 0<m<1283 1000!+m is
composite.
MATHEMATICA
a[n_] := (For[m = 1, ! PrimeQ[(10^n)! + m], m++ ]; m); Do[Print[a[n]], {n, 0, 3}]
sp[n_]:=Module[{c=(10^n)!}, NextPrime[c]-c]; Array[sp, 4, 0] (* Harvey P. Dale, Jul 29 2013 *)
CROSSREFS
Cf. A108519.
Sequence in context: A289716 A305141 A296592 * A346423 A077736 A068122
KEYWORD
more,nonn
AUTHOR
Farideh Firoozbakht, Jul 10 2005
STATUS
approved

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Last modified March 29 09:14 EDT 2024. Contains 371268 sequences. (Running on oeis4.)