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A362630
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Squarefree semiprimes (products of two distinct primes) whose factors are strong primes.
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0
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187, 319, 407, 451, 493, 629, 649, 697, 737, 781, 869, 1003, 1067, 1073, 1111, 1139, 1177, 1189, 1207, 1343, 1397, 1507, 1517, 1639, 1649, 1711, 1717, 1793, 1819, 1943, 1969, 2059, 2101, 2159, 2167, 2183, 2291, 2329, 2419, 2453, 2479, 2497, 2533, 2627, 2629, 2747, 2761, 2771, 2813, 2911, 2923, 2929, 2959
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OFFSET
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1,1
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COMMENTS
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Strong primes are primes such that prime(n) > (prime(n-1) + prime(n+1))/2.
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LINKS
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EXAMPLE
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187 = 11*17 and 11 > (7+13)/2, 17 > (13+19)/2.
319 = 11*29 and 11 > (7+13)/2, 29 > (23+31)/2.
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MATHEMATICA
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strongQ[p_] := p > 2 && 2*p > Total[NextPrime[p, {-1, 1}]]; Select[Range[1, 3000, 2], (f = FactorInteger[#])[[;; , 2]] == {1, 1} && AllTrue[f[[;; , 1]], strongQ] &] (* Amiram Eldar, Jun 21 2023 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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