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 A340519 #17 Mar 03 2023 10:06:35
%S A340519 6,8,18,16,30,24,42,32,54,40,66,48,78,56,90,64,102,72,114,80,126,88,
%T A340519 138,96,150,104,162,112,174,120,186,128,198,136,210,144,222,152,234,
%U A340519 160,246,168,258,176,270,184,282,192,294,200,306,208,318,216,330,224,342,232,354,240,366,248
%N A340519 Smallest order of a non-abelian group with a center of order n.
%C A340519 a(n) is 6n if n is odd and 4n if n is even. This is because the groups involved are C(n) X S3 if n is odd, where S3 is the symmetric group of order 6, and C(n/2) X D8 if n is even, where D8 is the dihedral group of order 8 and C(m) is the cyclic group of order m.
%C A340519 By Lagrange's Theorem a(n) is a multiple of n.
%t A340519 Table[If[OddQ[n],6n,4n],{n,100}] (* _Harvey P. Dale_, Mar 03 2023 *)
%Y A340519 Equals 2*A106833.
%Y A340519 Cf. A059806, A060702, A340518.
%K A340519 nonn
%O A340519 1,1
%A A340519 _Bob Heffernan_ and _Des MacHale_, Jan 24 2021; corrected Feb 14 2021