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A086172
Numbers n such that n*prime(n)+1 is prime.
11
1, 2, 4, 6, 24, 30, 36, 42, 72, 84, 98, 100, 116, 126, 128, 144, 162, 174, 206, 212, 228, 288, 312, 318, 324, 336, 350, 360, 406, 408, 416, 418, 452, 458, 466, 498, 510, 522, 528, 530, 536, 546, 548, 556, 604, 654, 660, 666, 682, 684, 690, 708, 710, 728, 738
OFFSET
1,2
COMMENTS
LINKS
MATHEMATICA
Select[Range[1000], PrimeQ[ # Prime[ # ]+1]&]
PROG
(Magma) [n: n in [1..800] | IsPrime(n*NthPrime(n) + 1)]; // Vincenzo Librandi, Oct 05 2012
(PARI) is(n, p=prime(n))=isprime(n*p+1) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Zak Seidov, Jul 11 2003
STATUS
approved