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A177013 a(n) is the smallest number m such that all the n numbers 1!*m-1, 2!*m-1, ..., n!*m-1 are prime. 1
3, 3, 3, 3, 3, 1500, 1500, 154770, 1656252, 3240034842 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
a(5)=3 because all five numbers 1!*3-1, 2!*3-1, 3!*3-1, 4!*3-1 and 5!*3-1 are prime and 3 is the smallest such number.
The corresponding primes are:
n=1: 2;
n=2: 2, 5;
n=3: 2, 5, 17;
n=4: 2, 5, 17, 71;
n=5: 2, 5, 17, 71, 359;
n=6: 1499, 2999, 8999, 35999, 179999, 1079999;
n=7: 1499, 2999, 8999, 35999, 179999, 1079999, 7559999;
n=8: 154769, 309539, 928619, 3714479, 18572399, 111434399, 780040799, 6240326399;
...
PROG
(PARI) okm(m, n) = {for (k=1, n, if (! isprime(k!*m-1), return (0)); ); return (1); }
a(n) = {m = 1; while(! okm(m, n), m++); m; } \\ Michel Marcus, Jun 08 2014
CROSSREFS
Cf. A177014.
Sequence in context: A105121 A290658 A264097 * A092282 A263998 A048181
KEYWORD
more,nonn
AUTHOR
STATUS
approved

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Last modified May 19 13:04 EDT 2024. Contains 372692 sequences. (Running on oeis4.)