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 A056670 #13 Oct 05 2024 09:08:50
%S A056670 1,1,1,1,1,2,1,1,3,3,1,2,2,2,3,3,1,2,1,2,2,2,1,2,5,5,5,5,3,3,3,3,3,3,
%T A056670 5,5,5,5,3,3,2,2,2,2,5,5,5,5,7,7,7,7,7,7,2,2,2,2,2,2,2,2,7,7,7,7,7,7,
%U A056670 3,3,1,2,2,2,5,5,7,7,7,7,7,7,3,3,5,5,5,5,3,3,7,7,7,7,7,7,5,5,3,3,3,3,3,3,3
%N A056670 Largest non-unitary prime factor of A001405(n) = binomial(n, floor(n/2)), or 1 if no such prime exists.
%C A056670 The largest prime divisor of A056057(n), the largest square divisor of binomial(n, floor(n/2)), or 1 if no such prime exists.
%H A056670 Amiram Eldar, <a href="/A056670/b056670.txt">Table of n, a(n) for n = 1..10000</a>
%F A056670 a(n) = A006530(A056057(n)).
%e A056670 For n = 28: binomial(28,14) = 2*2*2*3*3*3*5*5*17*19*23, so a(28) = 5.
%e A056670 For n = 342: binomial(342,171) = 32*F, where F is squarefree, so a(341) = 2.
%t A056670 a[n_] := Module[{f = Select[FactorInteger[Binomial[n, Floor[n/2]]], Last[#] > 1 &]}, If[f == {}, 1, f[[-1, 1]]]]; Array[a, 100] (* _Amiram Eldar_, Oct 05 2024 *)
%Y A056670 Cf. A001405, A006530, A056057, A056175.
%K A056670 nonn
%O A056670 1,6
%A A056670 _Labos Elemer_, Aug 10 2000