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A234098
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Primes of the form (p*q + 1)/2, where p and q are distinct primes.
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4
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11, 17, 29, 43, 47, 67, 71, 73, 89, 101, 103, 107, 109, 127, 151, 191, 197, 223, 227, 241, 251, 269, 277, 283, 317, 349, 359, 373, 397, 409, 433, 457, 461, 467, 487, 521, 541, 569, 571, 631, 643, 647, 659, 673, 701, 709, 719, 733, 739, 751, 757, 769, 821
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OFFSET
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1,1
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LINKS
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EXAMPLE
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11 = (3*7 + 1)/2, 17 = (5*7 + 1)/2.
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MATHEMATICA
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t = Select[Range[1, 7000, 2], Map[Last, FactorInteger[#]] == Table[1, {2}] &]; Take[(t + 1)/2, 120] (* A234096 *)
v = Flatten[Position[PrimeQ[(t + 1)/2], True]] ; w = Table[t[[v[[n]]]], {n, 1, Length[v]}] (* A233562 *)
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PROG
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(Haskell)
a234098 n = a234098_list !! (n-1)
a234098_list = filter ((== 1) . a010051') $
map ((flip div 2) . (+ 1)) a046388_list
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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