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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. 3
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

Table of n, a(n) for n=1..28.

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: A190413 A066696 A195006 * A069146 A235021 A184500

Adjacent sequences:  A114525 A114526 A114527 * A114529 A114530 A114531

KEYWORD

nonn

AUTHOR

Yasutoshi Kohmoto zbi74583(AT)boat.zero.ad.jp, 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 April 18 14:05 EDT 2014. Contains 240720 sequences.