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A066238
The floor(n/3)-perfect numbers, where f-perfect numbers for an arithmetical function f are defined in A066218.
0
2, 12, 18, 40, 56, 304, 550, 748, 1504, 3230, 3770, 6976, 29824, 124672, 351351, 382772, 510464, 537248, 698528, 791264, 1081568, 1279136, 2065408, 2279072, 211855016, 561841408, 731378944, 3365232128, 3557004544
OFFSET
1,1
COMMENTS
It appears that there are more floor(n/N)-perfect numbers the larger N is. (Here N = 3.)
LINKS
J. Pe, On a Generalization of Perfect Numbers, J. Rec. Math., 31(3) (2002-2003), 168-172.
EXAMPLE
Let f(n) = floor(n/3). Then f(12) = 6 = 3+2+1+0 = f(6)+f(4)+f(3)+f(1); so 12 is a term of the sequence.
MATHEMATICA
f[x_] := Floor[x/3]; Select[ Range[2, 10^5], 2 * f[ # ] == Apply[ Plus, Map[ f, Divisors[ # ] ] ] & ]
CROSSREFS
Cf. A066218.
Sequence in context: A325767 A335799 A190044 * A101074 A115109 A048001
KEYWORD
nonn,more
AUTHOR
Joseph L. Pe, Dec 19 2001
EXTENSIONS
a(14)-a(29) from Amiram Eldar, Sep 26 2019
STATUS
approved