

A118769


Primes of the form n!  n!! + 1.


1



17, 673, 39937, 87177646081, 6402373519933441, 304888344611712432172380979201, 126886932185884164103433389335161480802865515044406852999479261820223930701069680640000001
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OFFSET

1,1


COMMENTS

The next term  a(8)  has 675 digits.  Harvey P. Dale, Dec 17 2018


REFERENCES

G. Balzarotti and P. P. Lava, Le sequenze di numeri interi, Hoepli, 2008, p. 159.


LINKS

Table of n, a(n) for n=1..7.


EXAMPLE

For n=4, 4!  4!! + 1 = 4*3*2*1  4*2 + 1 = 24  8 + 1 = 17, which is prime.


MAPLE

SFACT:= proc(n) local i, j, k; for k from 1 by 1 to n do i:=k; j:=k2; while j >0 do i:=i*j; j:=j2; od: if isprime(k!i+1) then print(k!i+1); fi; od: end: SFACT(300);


MATHEMATICA

Select[Table[n!n!!+1, {n, 70}], PrimeQ] (* Harvey P. Dale, Dec 17 2018 *)


CROSSREFS

Sequence in context: A203170 A063941 A089018 * A009158 A012050 A012157
Adjacent sequences: A118766 A118767 A118768 * A118770 A118771 A118772


KEYWORD

nonn


AUTHOR

Paolo P. Lava and Giorgio Balzarotti, May 22 2006


STATUS

approved



