|
|
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
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
Trivial divisors of a number are 1 and the number itself, see A048050.
|
|
LINKS
|
|
|
FORMULA
|
|
|
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:
|
|
MATHEMATICA
|
#+Total[Most[Rest[Divisors[#]]]]&/@Select[Range[4, 200], !PrimeQ[#]&] (* Harvey P. Dale, Oct 28 2013 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|