login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A177052 Ceiling(n/2)-abundant numbers. 2
6, 12, 18, 20, 24, 28, 30, 36, 40, 42, 48, 54, 56, 60, 66, 70, 72, 78, 80, 84, 88, 90, 96, 100, 102, 104, 108, 112, 114, 120, 126, 132, 138, 140, 144, 150, 156, 160, 162, 168, 174, 176, 180, 186, 192, 196, 198, 200, 204, 208, 210, 216, 220, 222, 224, 228 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For definition, see A175522.

All positive numbers == 0 (mod 6) are in the sequence (basically A008588). In addition, note that all odd primes are ceiling(n/2)-deficient numbers. The first odd term of the sequence is 315.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

FORMULA

{n : Sum_{d|n, d<n} A004526(1+d) > A004526(1+n)}. [R. J. Mathar, Dec 11 2010]

PROG

(Sage) is_A177052 = lambda n: sum(ceil(d/2) for d in divisors(n)) > 2*ceil(n/2) # D. S. McNeil, Dec 10 2010

(PARI) isok(n) = sumdiv(n, d, (d<n)*ceil(d/2)) > ceil(n/2); \\ Michel Marcus, Feb 08 2016

CROSSREFS

Cf. A177050 (perfect version), A005100, A005101, A175524, A175526, A175811, A175821, A175853.

Sequence in context: A119357 A097216 A326133 * A023196 A204829 A005835

Adjacent sequences:  A177049 A177050 A177051 * A177053 A177054 A177055

KEYWORD

nonn

AUTHOR

Vladimir Shevelev, Dec 09 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 19 10:37 EST 2021. Contains 340269 sequences. (Running on oeis4.)