A100382 - OEIS

%I #14 Sep 08 2022 08:45:15

%S 3,7,13,31,127,307,1093,1723,2801,3541,8191,10303,19531,28057,30941,

%T 131071,147073,524287,797161,830833,1191373,1204507,1353733,1395943,

%U 1424443,1482307,1886503,2037757,2212657,2432041,2507473,2922391

%N Record values of A062700.

%C Take sequence A062700: 3, 7, 13, 31, 31, 127, 307, 1093, 1723, 2801, 3541, 8191, 5113, 8011, 10303, .... Then eliminate terms so that each term of the sequence is larger than the preceding one: 3, 7, 13, 31, 127, 307, 1093, 1723, 2801, 3541, 8191, 10303, ....

%H Chai Wah Wu, <a href="/A100382/b100382.txt">Table of n, a(n) for n = 1..10000</a>

%o (Magma) S:=[]; a:=0; for n in [1..3000000] do c:=SumOfDivisors(n); if IsPrime(c) and a lt c then Append(~S,c); a:=c; end if; end for; S; // _Klaus Brockhaus_, Oct 21 2009

%Y Cf. A062700 (terms of A000203 that are prime), A000203 (sigma(n), sum of divisors of n), A034885 (record values of sigma(n)).

%K nonn

%O 1,1

%A _Jorge Coveiro_, Dec 30 2004

%E More terms from _Ryan Propper_, Jul 13 2005

%E Edited, corrected and extended by _Klaus Brockhaus_, Oct 21 2009