cp's OEIS Frontend

A072745 Product of the members of pairs of primes (p, q) with p < q and such that, for some integer k, (p+q)/2 = 2^k and p > 2^(k-1).

%I A072745 #10 Jan 23 2022 07:37:32
%S A072745 15,55,247,799,943,4087,14359,14863,15943,51847,56887,59911,62287,
%T A072745 64807,65311,200143,208783,234919,245503,255583,259543,260119,262063,
%U A072745 848767,869647,884551,960367,974047,977287,983551,1003207,1026967
%N A072745 Product of the members of pairs of primes (p, q) with p < q and such that, for some integer k, (p+q)/2 = 2^k and p > 2^(k-1).
%F A072745 a(n) = A072742(n) * A072743(n).
%o A072745 (PARI) listkp(k) = {my(list = List()); forprime(p=2^(k-1)+1, 2^k, my(q=2^(k+1)-p); if ((q>p) && isprime(q), listput(list, q*p));); Vec(list);}
%o A072745 upto(k) = {my(list = List()); for (i=1, k, my(klist = listkp(i)); if (#klist, for (j=1, #klist, listput(list, klist[j])));); Vec(list);}
%o A072745 upto(11) \\ _Michel Marcus_, Jan 22 2022
%Y A072745 Cf. A072742, A072743, A072744.
%K A072745 nonn
%O A072745 1,1
%A A072745 _Reinhard Zumkeller_, Jul 08 2002
%E A072745 Name edited by _Michel Marcus_, Jan 22 2022