

A162195


Sum of proper divisors of nth nonprime number A018252(n).


2



0, 3, 6, 7, 4, 8, 16, 10, 9, 15, 21, 22, 11, 14, 36, 6, 16, 13, 28, 42, 31, 15, 20, 13, 55, 22, 17, 50, 54, 40, 33, 26, 76, 8, 43, 21, 46, 66, 17, 64, 23, 32, 108, 34, 41, 63, 19, 78, 58, 27, 74, 123, 40, 49, 64, 19, 90, 106, 40, 44, 140, 23, 46, 33, 92, 144, 21, 76, 35, 50, 25
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OFFSET

1,2


COMMENTS

The kth positive integer of this sequence is equal to the sum of proper divisors of kth composite number A002808(k).


LINKS

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


FORMULA

a(n) = A001065(A018252(n)).


MATHEMATICA

NonPrime[n_Integer] := FixedPoint[n + PrimePi@# &, n + PrimePi@n]; f[n_] := Block[{m = NonPrime@n}, DivisorSigma[1, m]  m]; Array[f, 71] (* Robert G. Wilson v, Aug 17 2009 *)
Table[If[PrimeQ[n], 1, Total[Most[Divisors[n]]]], {n, 100}]/.(1>Nothing) (* Harvey P. Dale, Dec 15 2017 *)


CROSSREFS

Cf. A001065, A018252, A002808, A162194, A162196.
Sequence in context: A264921 A098990 A336453 * A117361 A228787 A245220
Adjacent sequences: A162192 A162193 A162194 * A162196 A162197 A162198


KEYWORD

easy,nonn


AUTHOR

Omar E. Pol, Jul 04 2009


EXTENSIONS

a(17) and further terms from Robert G. Wilson v, Aug 17 2009


STATUS

approved



