%I A005276 M5291
%S A005276 48,75,140,195,1050,1575,1648,1925,2024,2295,5775,6128,8892,9504,16587,
%T A005276 20735,62744,75495,186615,196664,199760,206504,219975,266000,309135,312620
%N A005276 Betrothed (or quasi-amicable) numbers.
%C A005276 Members of a pair (m,n) such that sigma(m)=sigma(n)=m+n+1, where sigma=A000203. 
               [From M. F. Hasler (MHasler(AT)univ-ag.fr), Nov 04 2008]
%C A005276 Also members of a pair (m,k) such that m=sum of nontrivial divisors of 
               k and k=sum of nontrivial divsors of m. [From Juri-Stepan Gerasimov 
               (2stepan(AT)rambler.ru), Sep 11 2009]
%D A005276 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A005276 R. K. Guy, Unsolved Problems in Number Theory, B5.
%D A005276 P. Hagis and G. Lord, Quasi-amicable numbers, Math. Comp. 31 (1977), 
               608-611.
%H A005276 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               QuasiamicablePair.html">Link to a section of The World of Mathematics.</
               a>
%F A005276 A005276 = A003502 union A003503. [From M. F. Hasler (MHasler(AT)univ-ag.fr), 
               Nov 04 2008]
%o A005276 Contribution from M. F. Hasler (MHasler(AT)univ-ag.fr), Nov 04 2008: 
               (Start)
%o A005276 (PARI) isA005276(n) = { local(s=sigma(n)); s>n+1 & sigma(s-n-1)==s }
%o A005276 for( n=1, 10^6, isA005276(n) & print1(n",")) (End)
%Y A005276 Cf. A003502, A003503.
%Y A005276 Sequence in context: A033821 A165039 A057533 this_sequence A143722 A110229 
               A108608
%Y A005276 Adjacent sequences: A005273 A005274 A005275 this_sequence A005277 A005278 
               A005279
%K A005276 nonn,nice
%O A005276 1,1
%A A005276 N. J. A. Sloane (njas(AT)research.att.com).