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 A051539 #39 Jul 28 2025 05:37:15
%S A051539 1,5,45,585,9945,69615,348075,10094175,111035925,4108329225,
%T A051539 168441498225,168441498225,1179090487575,62491795841475,
%U A051539 1187344120988025,72427991380269525,72427991380269525,1665843801746199075,121606597527472532475,121606597527472532475
%N A051539 a(n) is the least common multiple of {1, 5, 9, 13, 17, ..., 4n+1} (A016813).
%C A051539 This sequence coincides with sequence A097328 of denominators of 1 + 1/5 + 1/9 + 1/13 + ... + 1/(4n+1) iff n < 12. - _T. D. Noe_, Aug 04 2004
%H A051539 Harvey P. Dale, <a href="/A051539/b051539.txt">Table of n, a(n) for n = 0..866</a> (first 201 terms from T. D. Noe)
%H A051539 <a href="/index/Lc#lcm">Index entries for sequences related to lcm's</a>
%e A051539 a(3) = LCM {1, 5, 9, 13} = 585.
%t A051539 Table[ Apply[ LCM, Join[{1}, Table[1 + 4i, {i, 0, n}]]], {n, 0, 19}]
%t A051539 nn=20;Table[LCM@@Take[4Range[0,nn-1]+1,n],{n,nn}] (* _Harvey P. Dale_, Jul 04 2011 *)
%t A051539 Table[LCM@@NestList[#+4&,1,n],{n,0,20}] (* _Harvey P. Dale_, Nov 21 2016 *)
%o A051539 (Magma) k:=77; [Lcm([h: h in [1..j by 4]]): j in [1..k by 4]]; // _Bruno Berselli_, May 03 2011
%o A051539 (PARI) a(n)=lcm(vector(n,i,4*n+1)) \\ _Charles R Greathouse IV_, Feb 09 2017
%Y A051539 Cf. A016813, A075136, A074598, A097329.
%K A051539 easy,nice,nonn
%O A051539 0,2
%A A051539 _Asher Auel_
%E A051539 Edited by _Robert G. Wilson v_, Aug 27 2002
%E A051539 a(16) corrected by _T. D. Noe_, Feb 08 2008