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 A275380 #14 Jul 27 2016 10:21:44 %S A275380 0,2,1,2,2,3,3,5,3,6 %N A275380 Number of odd prime factors (with multiplicity) of generalized Fermat number 7^(2^n) + 1. %F A275380 a(n) = A001222(A078304(n)) for n > 0. - _Felix Fröhlich_, Jul 25 2016 %e A275380 b(n) = (7^(2^n) + 1)/2. %e A275380 Complete Factorizations %e A275380 b(0) = 2*2 %e A275380 b(1) = 5*5 %e A275380 b(2) = 1201 %e A275380 b(3) = 17*169553 %e A275380 b(4) = 353*47072139617 %e A275380 b(5) = 7699649*134818753*531968664833 %e A275380 b(6) = 35969*1110623386241*15266848196793556098085000332888634369 %e A275380 b(7) = 257*769*197231873*6856531741041792239054980342217258517995521*P52 %e A275380 b(8) = 28667393*126575155274810369*P192 %e A275380 b(9) = 13313*943558259713* %e A275380 275102002206713516320479233*1338330888777063359811677099009* %e A275380 656929861401793262700329631944023570433*P321 %Y A275380 Cf. A078304, A273948. %K A275380 nonn,hard,more %O A275380 0,2 %A A275380 _Arkadiusz Wesolowski_, Jul 25 2016 %E A275380 a(9) was found by Nestor de Araújo Melo and Geoffrey Reynolds (2008)