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 A261206 #50 May 06 2024 01:48:40 %S A261206 1,2,4,6,12,36,132,144,156,900,3600,4032,7140,18360,44100,46440, %T A261206 4062240,9147600,999999000000 %N A261206 Numbers j such that ceiling(j^(1/k)) divides j for all integers k >= 1. %C A261206 Is this a finite sequence? %C A261206 It is possible to generalize this class of sequences by taking some integer-valued function f(j,k) decreasing in k such that f(j,1) = j and f(j,m) = c (for example, c=1 or c=2) for all sufficiently large m and considering those j that are divisible by all of f(j,1), f(j,2), ... If f(j,k) is slowly decreasing in k, then the set of corresponding j's is likely to have a very small number (if any) of terms, while if f(j,k) decreases rapidly, then there will be too many suitable j's. I believe the balance is achieved at functions like f(j,k) = floor(j^(1/k)) so that f(j,k) stabilizes to c at k ~= log(j). - _Max Alekseyev_, Aug 16 2015 %C A261206 If it exists, a(20) > 10^35. - _Jon E. Schoenfield_, Oct 17 2015 %o A261206 (PARI) is(n) = my(k,t); if(n==1,return(1)); if(n%2,return(0)); k=2; while( (t=ceil((n-.5)^(1/k)))>2, if(n%t,return(0)); k++); 1 %o A261206 n=1;while(n<10^5,if(is(n),print1(n,", "));n++) /* Able to generate terms < 10^5 */ \\ _Derek Orr_, Aug 12 2015 %Y A261206 Cf. A261205, A261341, A261342. %Y A261206 Subsequence of all of A087811, A002620, A261011, A261417. %K A261206 nonn,more,nice %O A261206 1,2 %A A261206 _Max Alekseyev_, Aug 11 2015