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 A131940 #8 Apr 30 2019 12:03:53
%S A131940 1,7,91,1729,43225,1339975,49579075,2131900225,14923301575,
%T A131940 164156317325,10013535356825,670906868907275,48976201430231075,
%U A131940 3869119912988254925,65775038520800333725,65775038520800333725,6380178736517632371325
%N A131940 Least common multiple of {1, 7, 13, 19, 25, ..., (6n+1)} (A016921).
%C A131940 This is to 6n+1 (A016921) as A051539 is to 4n+1 (A016813). Because 6*9 + 1 = 49 is divisible by 6*1 + 1 = 7, this sequence differs from A008542. a(n) | A008542(n+1).
%t A131940 a = {1}; Do[l = 1; For[j = 1, j < n, j++, l = LCM[l, 6*j + 1]]; AppendTo[a, l], {n, 2, 20}]; a (* _Stefan Steinerberger_, Oct 07 2007 *)
%t A131940 Join[{1},Table[LCM@@(6*Range[0,n]+1),{n,20}]] (* _Harvey P. Dale_, Apr 30 2019 *)
%Y A131940 Cf. A008542, A016813, A016921, A051539.
%K A131940 easy,nonn
%O A131940 0,2
%A A131940 _Jonathan Vos Post_, Oct 05 2007
%E A131940 More terms from _Stefan Steinerberger_, Oct 07 2007