A066238 The floor(n/3)-perfect numbers, where f-perfect numbers for an arithmetical function f are defined in A066218.
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
Examples
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.
Links
- J. Pe, On a Generalization of Perfect Numbers, J. Rec. Math., 31(3) (2002-2003), 168-172.
Crossrefs
Cf. A066218.
Programs
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Mathematica
f[x_] := Floor[x/3]; Select[ Range[2, 10^5], 2 * f[ # ] == Apply[ Plus, Map[ f, Divisors[ # ] ] ] & ]
Extensions
a(14)-a(29) from Amiram Eldar, Sep 26 2019
Comments