A066245 Floor(|x*sin(x)|)-perfect numbers, where f-perfect numbers for an arithmetical function f are defined in A066218.

3, 6, 10, 34, 50, 91, 222, 364, 1485, 6640, 18579, 775698, 1035507, 1706366, 46388515, 75714802

Offset

1,1

Links

Table of n, a(n) for n=1..16.

J. Pe, On a Generalization of Perfect Numbers, J. Rec. Math., 31(3) (2002-2003), 168-172.

Example

Let f(n) = floor(|x*sin(x)|). Then f(6) = 1 = 0+1+0 = f(3)+f(2)+f(1); so 6 is a term of the sequence.

Mathematica

f[x_] := Floor[Abs[x*Sin[x]]]; Select[ Range[2, 10^4], 2 * f[ # ] == Apply[ Plus, Map[ f, Divisors[ # ] ] ] & ]

Crossrefs

Cf. A066218.

Sequence in context: A001465 A094276 A151376 * A356977 A068821 A062100

Adjacent sequences: A066242 A066243 A066244 * A066246 A066247 A066248

Keyword

nonn,more

Author

Joseph L. Pe, Dec 19 2001

Extensions

a(11)-a(16) from Amiram Eldar, Sep 26 2019

Status

approved