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Arithmetic prime (Posted on 2019-04-25) Difficulty: 3 of 5
What is the smallest positive integer k such that k+1, 2k+1, 3k+1, 4k+1 are all primes?

No Solution Yet Submitted by Danish Ahmed Khan    
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re: computer solution - OEIS findings | Comment 2 of 3 |
(In reply to computer solution by Charlie)

The OEIS has a couple of sequences I found using Charlie's results:

A237189: "Numbers n such that n+1, 2n+1, 3n+1, 4n+1 are four primes."  330, 1530, 3060, 4260, 4950, 6840, 10830, 15390, 18120, 23010, ...

A088250 "a(n) = smallest number k such that rk + 1 is prime for all r = 1 to n."  1, 1, 2, 330, 10830, 25410, 512820, 512820, 12960606120, 434491727670, ...

  Posted by Brian Smith on 2019-04-26 01:21:09
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