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%I #21 Feb 21 2024 10:53:04
%S 5,125,1253,1673,3127,5191,7615,12035,43817,47795,48559,49955,56975,
%T 58373,61721,63545,68033,78395,97411,106001,108473,109939,111451,
%U 111683,123497,123797,131659,137081,192065,192279,224561,228377,274273,280313
%N Numbers n such that sigma(n+1) = 2*sigma(n).
%C Sequence seems to consist only of odd values.
%H Harry J. Smith, <a href="/A067081/b067081.txt">Table of n, a(n) for n = 1..761</a>
%t f[n_]:=DivisorSigma[1,n]; lst={};Do[If[2*f[n]==f[n+1],AppendTo[lst,n]],{n,9!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Jul 22 2009 *)
%o (PARI) { n=0; for (m=1, 10^10, if (sigma(m+1) == 2*sigma(m), write("b067081.txt", n++, " ", m); if (n==1000, return)) ) } \\ _Harry J. Smith_, May 08 2010
%K nonn
%O 1,1
%A _Benoit Cloitre_, Feb 18 2002
%E Terms added by _Harry J. Smith_, May 08 2010
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