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 A216897 #11 Jun 06 2025 08:33:37 %S A216897 3,12,1080,18506880,2198278051200,28657168334177779210174055055360000, %T A216897 30539655646420783598362725995379113771515252254037575464371359842304000000000 %N A216897 a(n) = smallest m such that sigma(m)/m = n + 1/3. %C A216897 a(7) is a 77-digit number with factorization: 2^35 3^20 5^9 7^3 11 13^2 17 19 23 29 31 37^2 41 61 67 71 73 109 137 409 521 547 1093 36809 368089. %C A216897 An upper bound for a(8) is a 165-digit number that can be found on given link where line begins with 25/3. %H A216897 Walter Nissen and Michel Marcus, <a href="http://upforthecount.com/math/blackf.txt">Extended Table of Abundancies</a> %e A216897 a(1) = 3 because sigma(3)/3 = 4/3 = 1 + 1/3 and 3 is the earliest m such that sigma(m)/m = 1 + 1/3. %Y A216897 Cf. A160320, A088912. %K A216897 nonn %O A216897 1,1 %A A216897 _Michel Marcus_, Sep 19 2012 %E A216897 a(7) confirmed and added by _Max Alekseyev_, Jun 06 2025