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 A234093 Integers of the form (p*q - 1)/2, where p and q are distinct primes. 9
 7, 10, 16, 17, 19, 25, 27, 28, 32, 34, 38, 42, 43, 45, 46, 47, 55, 57, 59, 61, 64, 66, 70, 71, 72, 77, 79, 80, 88, 91, 92, 93, 100, 101, 102, 104, 106, 107, 108, 109, 110, 117, 118, 123, 124, 126, 129, 132, 133, 143, 145, 147, 149, 150, 151, 152, 154, 159 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A102770 is subsequence. - Zak Seidov, Feb 21 2014 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 EXAMPLE (3*5 - 1)/2 = 7; (3*7 - 1)/2 = 10. MATHEMATICA t = Select[Range[1, 7000, 2], Map[Last, FactorInteger[#]] == Table[1, {2}] &]; Take[(t - 1)/2, 120] (* A234093 *) v = Flatten[Position[PrimeQ[(t - 1)/2], True]] ; w = Table[t[[v[[n]]]], {n, 1, Length[v]}] (* A233561 *) (w - 1)/2 (* A234095 *) (* Peter J. C. Moses, Dec 23 2013 *) With[{nn=60}, Take[Union[Select[(Times@@#-1)/2&/@Subsets[Prime[ Range[ nn]], {2}], IntegerQ]], nn]] (* Harvey P. Dale, Mar 08 2015 *) CROSSREFS Cf. A102770, A233561, A234095, A234096. Sequence in context: A088350 A085382 A083390 * A287567 A301451 A033817 Adjacent sequences: A234090 A234091 A234092 * A234094 A234095 A234096 KEYWORD nonn,easy AUTHOR Clark Kimberling, Dec 27 2013 STATUS approved

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Last modified May 31 18:54 EDT 2023. Contains 363068 sequences. (Running on oeis4.)