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A124409
Numbers k such that 2k+1, 4k+1, 6k+1 and 8k+1 are primes.
6
165, 765, 1530, 2130, 2475, 3420, 5415, 7695, 9060, 11505, 12705, 13020, 15885, 16650, 20055, 20745, 22530, 24915, 26940, 29670, 32925, 35070, 36885, 39270, 44370, 47730, 48465, 54735, 55860, 56310, 58860, 65655, 66600, 67365, 67650
OFFSET
1,1
LINKS
MATHEMATICA
Select[Range[68000], And @@ PrimeQ /@ ({2, 4, 6, 8}*# + 1) &] (* Ray Chandler, Nov 20 2006 *)
PROG
(PARI) is(k) = sum(j = 1, 4, isprime(2*j*k+1)) == 4; \\ Jinyuan Wang, Aug 04 2019
KEYWORD
nonn
AUTHOR
Artur Jasinski, Oct 31 2006
STATUS
approved