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A078884 Greater member p of a twin prime pair such that p-1 is 3-smooth.

%I A078884 #19 Sep 17 2019 12:03:47
%S A078884 5,7,13,19,73,109,193,433,1153,2593,139969,472393,786433,995329,
%T A078884 57395629,63700993,169869313,4076863489,10871635969,2348273369089,
%U A078884 56358560858113,79164837199873,84537841287169,150289495621633
%N A078884 Greater member p of a twin prime pair such that p-1 is 3-smooth.
%H A078884 Ray Chandler, <a href="/A078884/b078884.txt">Table of n, a(n) for n = 1..62</a> (terms < 10^1000, first 56 terms from Robert Israel)
%F A078884 a(n) = A027856(n) + 1 = A078883(n) + 2.
%e A078884 A000040(21)=73 and 73-1=72=2^3*3^2=A003586(17) and 73-2=71=A000040(20), therefore 73 is a term.
%p A078884 N:= 10^100:
%p A078884 sort(select(t -> isprime(t) and isprime(t-2),
%p A078884 [seq(seq(1+2^i*3^j,i=1..ilog2(floor(N/3^j))),j=0..floor(log[3](N)))])); # _Robert Israel_, May 14 2018
%t A078884 1 + Select[With[{n = 10^15}, Sort@ Flatten@ Table[2^p * 3^q, {p, 0, Log2@ n}, {q, 0, Log[3, n/(2^p)]}] ], AllTrue[# + {-1, 1}, PrimeQ] &] (* _Michael De Vlieger_, May 14 2018 *)
%Y A078884 Cf. A006512, A014574, A003586, A027856.
%Y A078884 Essentially the same as A060211.
%K A078884 nonn
%O A078884 1,1
%A A078884 _Reinhard Zumkeller_, Dec 11 2002