A162284 - OEIS

%I #11 Jun 17 2019 08:49:19

%S 1,81,18966025,135187129,164275489,350561925,445421025,598047025,

%T 649587169,748733769,850830561,960362325,1055925025,1341097641,

%U 1406175001,1476326929,1520766009,1536248025,1591004025,1735566525

%N Odd numbers n such that b(n) >= n and b(b(n)) >= n, where b(n) = A161942(n) = oddpart(sigma(n)).

%C Applying b a third time produces a smaller value for every number in this sequence up to 10^10, except 1.

%C Of the first 43 terms, only the following nine are not squares: 350561925, 960362325, 1591004025, 1735566525, 1753206525, 1831175325, 4558583925, 6745097205, 8766517725, and incidentally, all of them are terms of A228058. - _Antti Karttunen_, Jun 16 2019

%H Robert Gerbicz, <a href="/A162284/b162284.txt">Table of n,a(n) up to 10^10; n=1..43</a>

%H <a href="/index/O#opnseqs">Index entries for sequences where any odd perfect numbers must occur</a>

%Y Cf. A161942, A228058, A326042.

%K nonn

%O 1,2

%A _Franklin T. Adams-Watters_, Jun 29 2009

%E Values for n > 3 from _Robert Gerbicz_