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%I #29 Feb 20 2024 06:59:21
%S 954,1300,11142,38214,89484,152154,167784,254136,303280,473316,574716,
%T 813920,918080,1307022,2008360,3676242,9878244,10368512,12548754,
%U 19411480,22493262,42413484,77766486,81513816,157874000,240828972
%N Numbers n such that sigma(n) = sigma(n+1)+sigma(n-1).
%H Donovan Johnson and Giovanni Resta, <a href="/A073500/b073500.txt">Table of n, a(n) for n = 1..170</a> (terms < 10^13, first 50 terms from Donovan Johnson)
%F a(n) = A076528(n)-1 - _Alex Ratushnyak_, Jul 06 2013.
%t s1 = s2 = s3 = 0; Do[ s1 = s2; s2 = s3; s3 = DivisorSigma[1, n]; If[ s2 == s1 + s3, Print[n - 1]], {n, 1, 10^8}]
%Y Cf. A000203, A076528.
%K nonn
%O 1,1
%A _Benoit Cloitre_, Aug 27 2002
%E Edited and extended by _Robert G. Wilson v_, Oct 24 2002
%E a(25)-a(26) from _Donovan Johnson_, Feb 01 2009
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