cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A362640 Product of the larger primes, q, in the Goldbach partitions of 2n such that p + q = 2n, p <= q, and p,q prime (or 1 if no Goldbach partition of 2n exists).

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%I A362640 #12 Feb 16 2025 08:34:05
%S A362640 1,2,3,5,35,7,77,143,143,221,3553,4199,5681,391,7429,551,351509,
%T A362640 392863,589,24679,765049,47027,1175921,58642669,2318087,55883,
%U A362640 95041567,84323,2961799,5037203051,78647,367569469,14263488419,2257,403723843,22531226387,461671607,761740327
%N A362640 Product of the larger primes, q, in the Goldbach partitions of 2n such that p + q = 2n, p <= q, and p,q prime (or 1 if no Goldbach partition of 2n exists).
%H A362640 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GoldbachPartition.html">Goldbach Partition</a>
%H A362640 Wikipedia, <a href="http://en.wikipedia.org/wiki/Goldbach%27s_conjecture">Goldbach's conjecture</a>
%H A362640 <a href="/index/Go#Goldbach">Index entries for sequences related to Goldbach conjecture</a>
%H A362640 <a href="/index/Par#part">Index entries for sequences related to partitions</a>
%F A362640 a(n) = Product_{k=1..n} (2n - k)^(c(k)*c(2n - k)), where c is the prime characteristic (A010051).
%F A362640 a(n) = Product_{p+q = 2n, p<=q, and p,q prime} q.
%F A362640 a(n) = A337568(n) / A362641(n).
%e A362640 a(10) = 221; 2*10 = 20 has two Goldbach partitions, namely 17+3 and 13+7. The product of the larger parts of these partitions, is 17*13 = 221.
%t A362640 Table[Product[(2 n - k)^((PrimePi[k] - PrimePi[k - 1]) (PrimePi[2 n - k] - PrimePi[2 n - k - 1])), {k, n}], {n, 40}]
%Y A362640 Cf. A010051, A045917, A337568 (product of all prime parts), A362641 (product of smaller primes p).
%K A362640 nonn,easy
%O A362640 1,2
%A A362640 _Wesley Ivan Hurt_, Apr 28 2023