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 A121360 #9 Dec 02 2024 18:28:23 %S A121360 2,1,8,14,26,62,134,393,1257,4659,9314,27933,167073,334142,4677862, %T A121360 14033577,56134292,2133102298,11788191218,52541651594,536226160966, %U A121360 2681130804805,8512643845707,129535245187539 %N A121360 Smallest k such that A002217(k)=n. %C A121360 Least number which becomes prime or 0 or 4 after n-1 iterations of f(x) = sum of prime factors of x (cf. A001414). Agrees with A048133 except for the second term. %C A121360 a(21) <= 536226160966. a(22) <= 2681130804805. a(23) <= 8512643845707. - _Donovan Johnson_, Oct 16 2010 %C A121360 a(25) <= 1679460336114602. - _Danila Potapov_, Dec 01 2024 %Y A121360 Cf. A002217, A001414, A048133. %K A121360 nonn,more %O A121360 1,1 %A A121360 _Klaus Brockhaus_, Jul 27 2006 %E A121360 a(19)-a(20) from _Donovan Johnson_, Oct 16 2010 %E A121360 a(21)-a(24) from _Danila Potapov_, Dec 01 2024