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 A056607 #17 Mar 02 2025 08:00:14 %S A056607 2,3,10,35,231,3003,14586,138567,5311735,154040315,434113615, %T A056607 16062203755,354604036745,15247973580035,286661903304658, %U A056607 7596540437573437,79093391614735197,4824696888498847017,85067024086690197405,6039758710155004015755,230948868774022296411965 %N A056607 a(n) is the n-th primorial divided by squarefree kernel of corresponding central binomial coefficient. %H A056607 Amiram Eldar, <a href="/A056607/b056607.txt">Table of n, a(n) for n = 1..383</a> %F A056607 a(n) = A002110(n)/A048633(n). %e A056607 For n = 6, A002110(6) = 30030, C(6,3) = 20 with squarefree kernel 10. So, a(6) = 30030/10 = 3003 = 3*7*11*13, which is also squarefree. %t A056607 a[n_] := Times @@ Prime[Range[n]] / Times @@ FactorInteger[Binomial[n, Floor[n/2]]][[;;, 1]]; Array[a, 21] (* _Amiram Eldar_, Mar 01 2025 *) %o A056607 (PARI) a(n) = prod(k=1, n, prime(k))/factorback(factor(binomial(n, n\2))[, 1]); \\ _Michel Marcus_, Jul 13 2018 %Y A056607 Cf. A002110, A001405, A048633. %K A056607 nonn %O A056607 1,1 %A A056607 _Labos Elemer_, Aug 07 2000