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A163871
The n-th composite plus the sum of its nontrivial divisors.
1
6, 11, 14, 12, 17, 27, 23, 23, 30, 38, 41, 31, 35, 59, 30, 41, 39, 55, 71, 62, 47, 53, 47, 90, 59, 55, 89, 95, 83, 77, 71, 123, 56, 92, 71, 97, 119, 71, 119, 79, 89, 167, 95, 103, 126, 83, 143, 125, 95, 143, 194, 113, 123, 139, 95, 167, 185, 120, 125, 223, 107, 131, 119, 179
OFFSET
1,1
COMMENTS
Trivial divisors of a number are 1 and the number itself, see A048050.
LINKS
FORMULA
a(n) = A002808(n) + A062825(n+1).
EXAMPLE
a(1) = 4 + 2 = 6;
a(2) = 6 + 5 = 11;
a(3) = 8 + 6 = 14.
MAPLE
A002808 := proc(n) local resul, i ; i := 1 ; resul := 4 ; while i < n do resul := resul+1 ; while isprime(resul) do resul := resul+1 ; od ; i := i+1 ; od; RETURN(resul) ; end:
A048050 := proc(n) if n <= 3 then 0; else numtheory[sigma](n)-n-1 ; fi; end:
A163871 := proc(n) A002808(n)+A048050(A002808(n)) ; end: seq(A163871(n), n=1..80) ; # R. J. Mathar, Aug 11 2009
MATHEMATICA
#+Total[Most[Rest[Divisors[#]]]]&/@Select[Range[4, 200], !PrimeQ[#]&] (* Harvey P. Dale, Oct 28 2013 *)
CROSSREFS
Cf. A027750.
Sequence in context: A315373 A154293 A199717 * A201915 A237606 A264935
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
a(4) corrected by R. J. Mathar, Aug 11 2009
STATUS
approved