

A087146


Numbers n such that n!+(n+1)!1 is prime.


1



1, 2, 3, 5, 9, 13, 14, 17, 27, 28, 33, 39, 103, 115, 205, 291, 1431, 1532, 1710, 1937, 3901, 3981, 4682, 6569, 20266, 20662
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OFFSET

1,2


COMMENTS

291 is in the sequence and also is in the sequence A087147, thus (291!+292!1,291!+292!+1) is a twin pair of primes. Any additional terms are greater than 1800 with the next prime having more than 5086 digits.
a(27) > 25000.  Robert Price, Jul 12 2015
a(1)a(26) give certified primes.  Robert Price, Jul 12 2015


REFERENCES

H. Dubner, Factorial and primorial primes, J. Rec. Math., 19(No. 3, 1987)


LINKS

Table of n, a(n) for n=1..26.


EXAMPLE

3 is in the sequence because 3!+4!1=29 is prime.


MATHEMATICA

v={}; Do[If[PrimeQ[n!+(n+1)!1], v=Append[v, n]; Print[v]], {n, 1800}]; v


CROSSREFS

Cf. A087147, A051856.
Sequence in context: A000861 A108168 A245905 * A033945 A098142 A270812
Adjacent sequences: A087143 A087144 A087145 * A087147 A087148 A087149


KEYWORD

nonn


AUTHOR

Farideh Firoozbakht, Aug 19 2003


EXTENSIONS

One more term from Ryan Propper, Aug 13 2005
a(21)a(26) from Robert Price, Jul 12 2015


STATUS

approved



