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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. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Eric Weisstein's World of Mathematics, Sociable Numbers
PROG
(PARI) S(n)=sigma(abs(n))-3*n
is(n)=S(S(S(S(n))))==n \\ Charles R Greathouse IV, Jan 16 2012
CROSSREFS
Cf. A113285, A114529. Contains A069146 as a subsequence.
Sequence in context: A252675 A066696 A195006 * A069146 A251648 A235021
KEYWORD
nonn
AUTHOR
Yasutoshi Kohmoto, Feb 15 2006
EXTENSIONS
a(5)-a(12) from Charles R Greathouse IV, Jan 20 2010
a(13)-a(28) from Donovan Johnson, Jan 16 2012
STATUS
approved

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Last modified July 12 06:35 EDT 2024. Contains 374237 sequences. (Running on oeis4.)