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A234096 Integers of the form (p*q + 1)/2, where p and q are distinct primes. 6

%I #5 Dec 04 2016 19:46:33

%S 8,11,17,18,20,26,28,29,33,35,39,43,44,46,47,48,56,58,60,62,65,67,71,

%T 72,73,78,80,81,89,92,93,94,101,102,103,105,107,108,109,110,111,118,

%U 119,124,125,127,130,133,134,144,146,148,150,151,152,153,155,160

%N Integers of the form (p*q + 1)/2, where p and q are distinct primes.

%F 1 + A234093.

%e (3*5 + 1)/2 = 8, (3*7 + 1)/2 = 11.

%t t = Select[Range[1, 7000, 2], Map[Last, FactorInteger[#]] == Table[1, {2}] &]; Take[(t + 1)/2, 120] (* A234096 *)

%t v = Flatten[Position[PrimeQ[(t + 1)/2], True]] ; w = Table[t[[v[[n]]]], {n, 1, Length[v]}] (* A233562 *)

%t (w + 1)/2 (* A234098 *) (* _Peter J. C. Moses_, Dec 23 2013 *)

%Y Cf. A234093, A233562, A234098.

%K nonn,easy

%O 1,1

%A _Clark Kimberling_, Dec 27 2013

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Last modified September 7 12:03 EDT 2024. Contains 375730 sequences. (Running on oeis4.)