A114528 Let S(n)=sigma(|n|)-3*n; sequence gives numbers n such that S(S(S(S(n))))=n. May be called {3,1}-Sociable number of orders 1 or 2 or 4.

1248, 1596, 28272, 30240, 32760, 463296, 678032, 1906128, 2178540, 4694328, 4697616, 4698072, 11110976, 12865770, 23569920, 30998250, 31235904, 37501072, 45532800, 63723600, 76980288, 95801088, 142990848, 146078592, 163032720, 614533696, 1044244800, 1379454720

Offset: 1

Author

Yasutoshi Kohmoto, Feb 15 2006

Keywords

• nonn

Links

• Eric Weisstein's World of Mathematics, Sociable Numbers

Crossrefs

Cf. A113285, A114529. Contains A069146 as a subsequence.

Programs

PARI

S(n)=sigma(abs(n))-3*n
is(n)=S(S(S(S(n))))==n \\ Charles R Greathouse IV, Jan 16 2012

Extensions

a(5)-a(12) from Charles R Greathouse IV, Jan 20 2010

a(13)-a(28) from Donovan Johnson, Jan 16 2012