login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A166983 The n-th composite minus the number of its divisors. 0
1, 2, 4, 6, 6, 6, 10, 11, 11, 12, 14, 17, 18, 16, 22, 22, 23, 22, 22, 26, 29, 30, 31, 27, 34, 35, 32, 34, 38, 39, 42, 38, 46, 44, 47, 46, 46, 51, 48, 53, 54, 48, 58, 57, 57, 61, 58, 62, 65, 62, 60, 70, 69, 70, 73, 70, 70, 76, 78, 72, 81, 82, 83, 80, 78, 87, 86, 89, 90, 91, 84 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..71.

FORMULA

a(n)=A002808(n)-A000005(A002808(n)) = A002808(n)-A035004(n+1).

EXAMPLE

a(1)=4-3=1, a(2)=6-4=2, a(3)=8-4=4.

MATHEMATICA

With[{comps=Rest[Complement[Range[100], Prime[Range[PrimePi[100]]]]]}, #-DivisorSigma[0, #]&/@comps] (* Harvey P. Dale, Dec 16 2011 *)

CROSSREFS

Cf. A000005, A002808.

Sequence in context: A050825 A174342 A111150 * A078611 A211376 A278249

Adjacent sequences:  A166980 A166981 A166982 * A166984 A166985 A166986

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Oct 26 2009

EXTENSIONS

Formula and two entries corrected by R. J. Mathar, May 21 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 September 17 19:12 EDT 2019. Contains 327137 sequences. (Running on oeis4.)