

A039725


Even abundant numbers divided by 2.
(Formerly N1690)


3



6, 9, 10, 12, 15, 18, 20, 21, 24, 27, 28, 30, 33, 35, 36, 39, 40, 42, 44, 45, 48, 50, 51, 52, 54, 56, 57, 60, 63, 66, 69, 70, 72, 75, 78, 80, 81, 84, 87, 88, 90, 93, 96, 98, 99, 100, 102, 104, 105, 108, 110, 111, 112, 114, 117, 120, 123, 126, 129, 130, 132, 135, 136
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OFFSET

1,1


COMMENTS

While the first even abundant number is 12 = 2^2*3, the first odd abundant is 945 = 3^3*5*7, the 232nd abundant number!
The asymptotic density of this sequence is in the interval (0.491096, 0.491156) (based on the known bounds on the densities of A005101 and A005231; see A302991 and A322287).  Amiram Eldar, Mar 11 2024


REFERENCES

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).


LINKS



FORMULA



EXAMPLE

The first even abundant number is 12, so 12/2 = 6 is the first element in this sequence.


MATHEMATICA

Select[Range[2, 300, 2], DivisorSigma[1, #]>2*#&]/2 (* Harvey P. Dale, Mar 22 2020 *)


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



