OFFSET
1,3
COMMENTS
n!10 = Product_{k=0..floor((n-1)/10)}(n - 10k).
a(61) > 50000. - Robert Price, Jun 10 2012
The first 11 primes associated with this sequence: 3, 3, 5, 7, 11, 13, 41, 173, 233, 1877, 293603. - Robert Price, Mar 10 2017
a(67) > 10^5. - Robert Price, Mar 31 2017
LINKS
C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75.
Ken Davis, Status of Search for Multifactorial Primes.
Nathan Russell, n!10+2 results, primenumbers group, Jan 2012.
Nathan Russell, n!10+2 results, message 23995 in primenumbers Yahoo group, Jan 17, 2012.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 10] + 2] &]
PROG
(PARI) for(n=0, 9999, isprime(prod(i=0, (n-2)\10, n-10*i)+2)& print1(n", "))
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
M. F. Hasler, Jan 17 2012
EXTENSIONS
a(40)-a(59) from Robert Price, Jun 10 2012
Inserted missing term of 6789 by Robert Price, Mar 10 2017
a(61)-a(66) from Robert Price, Mar 31 2017
STATUS
approved