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 A127181 #13 Aug 13 2025 06:15:08
%S A127181 1,1,2,3,5,11,37,221,3361,190777,83199527,760382931109,
%T A127181 662056785094857629,538451433632092674800570837,
%U A127181 12495147956629620251492228703104952798089,1397663545252630798358314360015943050984074671707253231083973
%N A127181 a(1)=a(2)=1. a(n) = smallest possible (product of b(k)'s + product of c(k)'s), where the sequence's terms a(1) through a(n-1) are partitioned somehow into {b(k)} and {c(k)}.
%C A127181 Every term of the sequence is coprime to every other term.
%H A127181 Max Alekseyev, <a href="/A127181/b127181.txt">Table of n, a(n) for n = 1..30</a>
%e A127181 By partitioning (a(1),a(2),...a(7)) = (1,1,2,3,5,11,37) into {b(k)} and {c(k)} so that {b(k)} = (1,2,5,11) and {c(k)} = (1,3,37), then (product of b(k)'s + product of c(k)'s) is minimized. Therefore a(8) = 1*2*5*11 + 1*3*37 = 221.
%t A127181 Nest[ Module[ {prod=Times@@#1}, Append[ #,Min[ #+prod/#&/@Times@@@Union[ Subsets[ # ] ] ] ] ]&,{1,1,2,3},12 ] (* Peter Pein (petsie(AT)dordos.net), Jan 07 2007 *)
%Y A127181 Cf. A127180.
%K A127181 nonn
%O A127181 1,3
%A A127181 _Leroy Quet_, Jan 07 2007
%E A127181 a(10)-a(15) from Peter Pein (petsie(AT)dordos.net), Jan 07 2007
%E A127181 a(16)-a(30) from _Max Alekseyev_, Apr 08 2022