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A114529 Let S(n)=sigma(|n|)/2-n; sequence gives numbers n such that S(S(S(S(n))))=n. May be called {1,2}-sociable number of orders 1 or 2 or 4. 3

%I

%S 41,929,1301,30240,32760,260609,1441440,1860768,2178540,3205440,

%T 3378240,3423420,3914820,4029480,4437720,5738040,6093360,6807240,

%U 7136640,7239120,7551360,9402120,10204740,12270720,12405120,12942720,13495680,14627340,14725620

%N Let S(n)=sigma(|n|)/2-n; sequence gives numbers n such that S(S(S(S(n))))=n. May be called {1,2}-sociable number of orders 1 or 2 or 4.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SociableNumbers.html">Sociable Numbers</a>

%Y Cf. A113285, A114528.

%K nonn

%O 1,1

%A _Yasutoshi Kohmoto_, Feb 15 2006

%E a(7)-a(29) from _Charles R Greathouse IV_, Nov 12 2010.

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Last modified May 11 15:11 EDT 2021. Contains 343791 sequences. (Running on oeis4.)