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 A293541 #8 Oct 13 2017 09:11:58 %S A293541 1,3,15,909,306915,36181647,25342642989 %N A293541 a(1)=1; for n>1, a(n) = least integer greater than a(n-1) such that the numbers of divisors of the pairwise sums of a(1),...,a(n) are all distinct. %e A293541 Let d(n) be the number of divisors of n. Then a(2)!=2 because d(1+1)=d(1+2)=2. a(2)=3 because d(1+1)=2, d(1+3)=3, and d(3+3)=4 are all distinct. %Y A293541 Cf. A000005, A293542, A005282. %K A293541 more,nonn %O A293541 1,2 %A A293541 _Logan J. Kleinwaks_, Oct 11 2017