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 A340483 #15 Jan 16 2021 01:25:32 %S A340483 3,9,105,1365,884037 %N A340483 a(n) is the smallest product of n (not necessarily distinct) odd primes m = p_1*p_2*...*p_n such that (d+m/d)/2 is a prime for all d dividing m. %C A340483 This sequence differs from A128281 only in the value A128281(2)=21: a(2)=9 since, for n=2 only, the specification "distinct primes" makes a difference. %e A340483 a(2) = 9 = 3*3 since (1+9)/2=5 and (3+3)/2=3. %Y A340483 Cf. A128281, A128283, A340482. %K A340483 nonn,hard,more %O A340483 1,1 %A A340483 _Hartmut F. W. Hoft_, Jan 09 2021