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 A090856 #9 Jun 06 2016 22:23:03 %S A090856 1,7,27,104,378,1327,4553,15351,51072,168147,548915,1779377,5734022, %T A090856 18384612,58688163,186632570,591509670,1869118923,5890466415, %U A090856 18518945789,58094637801,181884111404,568416743474,1773443888599 %N A090856 a(n) is the least positive integer such that the integer part of the arithmetic-geometric mean of a(n) and 1 is equal to 3^n. %F A090856 floor( agm(a(n), 1) ) = 3^n, for n>=0. %Y A090856 Cf. A090852, A090854, A090857. %K A090856 nonn %O A090856 0,2 %A A090856 _Paul D. Hanna_, Dec 10 2003