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 A080397 #17 Jun 21 2024 06:38:31 %S A080397 1,2,6,10,70,42,462,858,4290,24310,92378,176358,1352078,520030,222870, %T A080397 6463230,200360130,129644790,907513530,1767263190,22974421470, %U A080397 134564468610,526024740930,22870640910,1074920122770,1504888171878,1967930686302,34766775458002,1912172650190110 %N A080397 Largest squarefree number dividing central binomial coefficient A000984(n). %H A080397 Amiram Eldar, <a href="/A080397/b080397.txt">Table of n, a(n) for n = 0..1000</a> %F A080397 a(n) = A007947(A000984(n)). %p A080397 a := n -> convert(numtheory:-factorset(binomial(2*n, n)), `*`): %p A080397 seq(a(n),n=0..25); # _Peter Luschny_, Oct 31 2015 %t A080397 a[n_] := Times @@ FactorInteger[Binomial[2n, n]][[All, 1]]; Array[a, 26, 0] (* _Jean-François Alcover_, Jun 04 2019 *) %o A080397 (PARI) a(n) = vecprod(factor(binomial(2*n, n))[, 1]); \\ _Amiram Eldar_, Jun 21 2024 %Y A080397 Cf. A007947, A000984, A001405, A048633. %K A080397 nonn %O A080397 0,2 %A A080397 _Labos Elemer_, Mar 19 2003 %E A080397 More terms from _Amiram Eldar_, Jun 21 2024