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 A165497 #11 Jul 22 2025 07:23:30 %S A165497 1,3,3,60,60,201,481,5989,3122037,4434429,13576837,183894465, %T A165497 187925171,209072257,1498642520,12239200420,20220712468,20220712468, %U A165497 875023683404,992997544772,2721798771116,9770941874212,9770941874212 %N A165497 a(n) starts arithmetic progression of n terms separated by tau(a(n)), each term having the same number of divisors. %C A165497 a(15) > 10^9. %C A165497 a(19) > 10^11. - _Donovan Johnson_, Sep 24 2009 %C A165497 a(24) > 10^13. - _Giovanni Resta_, Aug 02 2013 %e A165497 tau(60) = tau(72) = tau(84) = tau(96) = tau(108) = 12. This is the first such progression of length greater than 3, so a(4) and a(5) are both 60. %o A165497 (PARI) has(n)=my(t=numdiv(n),s=1); while(numdiv(n+=t)==t, s++); s %o A165497 a(n)=my(k); while(has(k++)<n,); k \\ _Charles R Greathouse IV_, Apr 24 2015 %Y A165497 Cf. A064491, A165498, A165499. %K A165497 hard,nonn,more %O A165497 1,2 %A A165497 _Hugo van der Sanden_, Sep 21 2009 %E A165497 a(15)-a(18) from _Donovan Johnson_, Sep 24 2009 %E A165497 a(19)-a(23) from _Giovanni Resta_, Aug 02 2013