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A156167
Numbers n such that n![7]-1 is prime (where n![7] = A114799(n) = septuple factorial).
10
3, 4, 6, 8, 9, 10, 11, 12, 14, 17, 20, 24, 30, 31, 32, 46, 52, 54, 59, 98, 104, 143, 145, 160, 174, 198, 199, 202, 212, 215, 254, 371, 382, 452, 674, 739, 959, 1249, 1657, 2291, 2553, 2650, 3562, 3727, 3853, 4389, 4604, 5449, 5659, 6026, 6878, 7900, 9564, 10150, 12444, 13321, 22642, 24014, 26598, 27430, 31386, 40707, 43328, 45811
OFFSET
1,1
COMMENTS
a(65) > 50000. - Robert Price, Sep 09 2012
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[0, 1000], PrimeQ[MultiFactorial[#, 7] - 1] & ] (* Robert Price, Apr 19 2019 *)
PROG
(PARI) mf(n, k=7)=prod(i=0, (n-2)\k, n-i*k)
for( n=1, 9999, ispseudoprime(mf(n)-1) & print1(n", "))
KEYWORD
nonn
AUTHOR
M. F. Hasler, Feb 10 2009
EXTENSIONS
a(43)-a(64) from Robert Price, Sep 09 2012
STATUS
approved