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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
OFFSET
1,2
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
Sequence in context: A050825 A174342 A111150 * A361689 A078611 A211376
KEYWORD
nonn
AUTHOR
EXTENSIONS
Formula and two entries corrected by R. J. Mathar, May 21 2010.
STATUS
approved