A076528 - OEIS

%I #15 Jul 23 2015 17:27:26

%S 955,1301,11143,38215,89485,152155,167785,254137,303281,473317,574717,

%T 813921,918081,1307023,2008361,3676243,9878245,10368513,12548755,

%U 19411481,22493263,42413485,77766487,81513817,157874001,240828973

%N Numbers n such that sigma(n) = sigma(n-1) - sigma(n-2).

%H Giovanni Resta, <a href="/A076528/b076528.txt">Table of n, a(n) for n = 1..170</a> (terms < 10^13)

%F a(n) = A073500(n)+1 - _Alex Ratushnyak_, Jul 06 2013.

%e sigma(955) = 1152 sigma(954) = 2106 sigma(953) = 954 and 1152 = 2106 - 954; hence 955 is a term of the sequence.

%t Select[Range[3, 10^5], DivisorSigma[1, # ] == DivisorSigma[1, # - 1] - DivisorSigma[1, # - 2] &]

%Y Cf. A000203, A073500.

%K nonn

%O 1,1

%A _Joseph L. Pe_, Oct 18 2002

%E a(6)-a(26) from _Donovan Johnson_, Feb 01 2009