A163871 The n-th composite plus the sum of its nontrivial divisors.

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

Harvey P. Dale, Table of n, a(n) for n = 1..1000

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

Adjacent sequences: A163868 A163869 A163870 * A163872 A163873 A163874

Keyword

nonn,easy

Author

Juri-Stepan Gerasimov, Aug 06 2009

Extensions

a(4) corrected by R. J. Mathar, Aug 11 2009

Status

approved