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.
%I A362641 #10 Feb 16 2025 08:34:05 %S A362641 1,2,3,3,15,5,21,15,35,21,165,385,273,55,1001,39,2805,7735,133,561, %T A362641 13585,273,5865,124355,5187,1265,391391,741,27115,19605131,1767,64515, %U A362641 5766215,217,374187,12212915,313131,170085,142635185,63973,902451,13147103255,223041,101065,818183948197 %N A362641 Product of the smaller primes, p, 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 A362641 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GoldbachPartition.html">Goldbach Partition</a> %H A362641 Wikipedia, <a href="http://en.wikipedia.org/wiki/Goldbach%27s_conjecture">Goldbach's conjecture</a> %H A362641 <a href="/index/Go#Goldbach">Index entries for sequences related to Goldbach conjecture</a> %H A362641 <a href="/index/Par#part">Index entries for sequences related to partitions</a> %F A362641 a(n) = Product_{k=1..n} k^(c(k)*c(2n - k)), where c is the prime characteristic (A010051). %F A362641 a(n) = Product_{p+q = 2n, p<=q, and p,q prime} p. %F A362641 a(n) = A337568(n) / A362640(n). %e A362641 a(10) = 21; 2*10 = 20 has two Goldbach partitions, namely 17+3 and 13+7. The product of the smaller parts of these partitions, is 3*7 = 21. %t A362641 Table[Product[k^((PrimePi[k] - PrimePi[k - 1]) (PrimePi[2 n - k] - PrimePi[2 n - k - 1])), {k, n}], {n, 40}] %Y A362641 Cf. A010051, A045917, A337568 (product of all prime parts), A362640 (product of the larger primes q). %K A362641 nonn,easy %O A362641 1,2 %A A362641 _Wesley Ivan Hurt_, Apr 28 2023