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 A350120 #20 Jan 04 2022 16:58:51 %S A350120 1,5,22,33,5951,124,90088,187,757,1149,237152823,852,30744479715, %T A350120 207737,15555,876,40828735337636,1541,2932093694892923,8454,3557030, %U A350120 802103321,1895798161468690610 %N A350120 a(n) is the least integer k such that A350090(k) = 2*n-1 or -1 if no such k exists. %C A350120 Most terms of A350090 are odd. It is conjectured by _Klaus Purath_ that all odd numbers appear in A350090. %C A350120 a(n) is the least k such that tau(3*k*(k+1)+1) = 2*n. - _Jinyuan Wang_, Dec 19 2021 %C A350120 a(11) >= 10^8 if it exists. - _Michel Marcus_, Dec 20 2021 %o A350120 (PARI) a(n) = my(k=1, m=2*n); while (numdiv(3*k*(k+1)+1) != m, k++); k; \\ _Michel Marcus_, Dec 20 2021 %Y A350120 Cf. A000005 (tau), A002378, A003215, A350090. %K A350120 nonn,more %O A350120 1,2 %A A350120 _Michel Marcus_, Dec 15 2021 %E A350120 a(11)-a(23) from _Klaus Purath_, Jan 04 2022