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.

41, 929, 1301, 30240, 32760, 260609, 1441440, 1860768, 2178540, 3205440, 3378240, 3423420, 3914820, 4029480, 4437720, 5738040, 6093360, 6807240, 7136640, 7239120, 7551360, 9402120, 10204740, 12270720, 12405120, 12942720, 13495680, 14627340, 14725620

Offset: 1

Author

Yasutoshi Kohmoto, Feb 15 2006

Keywords

• nonn

Links

• Eric Weisstein's World of Mathematics, Sociable Numbers

Crossrefs

Cf. A113285, A114528.

Extensions

a(7)-a(29) from Charles R Greathouse IV, Nov 12 2010.