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A242333
Numbers k such that k^2 + 5 is a semiprime.
7
1, 2, 3, 4, 8, 9, 14, 18, 21, 22, 24, 26, 27, 28, 30, 33, 42, 44, 51, 54, 57, 58, 62, 63, 64, 68, 69, 82, 84, 86, 90, 93, 98, 99, 102, 104, 108, 111, 118, 132, 134, 138, 144, 152, 154, 156, 166, 174, 177, 180, 183, 184, 186, 188, 189, 194, 208, 210, 212, 216
OFFSET
1,2
COMMENTS
The semiprimes of this form are: 6, 9, 14, 21, 69, 86, 201, 329, 446, 489, 581, 681, 734, 789, 905, 1094, 1769, 1941, 2606, 2921, 3254, ...
LINKS
MATHEMATICA
Select[Range[0, 300], PrimeOmega[#^2 + 5] == 2 &]
PROG
(Magma) IsSemiprime:=func<i | &+[d[2]: d in Factorization(i)] eq 2>; [n: n in [0..300] | IsSemiprime(s) where s is n^2+5];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, May 14 2014
STATUS
approved