1,1

Amiram Eldar, Table of n, a(n) for n = 1..10000

a(n) = A001065(A001358(n)). - Amiram Eldar, Sep 23 2019

a(1)=3 because sum of aliquot divisors of first semiprime i.e. 4 is 1+2=3.

s[n_] := DivisorSigma[1, n] - n; s /@ Select[Range[300], PrimeOmega[#]==2 &] (* Amiram Eldar, Sep 23 2019 *)

Cf. A001065, A001358.

Sequence in context: A154890 A248176 A100000 * A021278 A336761 A143940

Adjacent sequences: A083679 A083680 A083681 * A083683 A083684 A083685

easy,nonn

Shyam Sunder Gupta, Jun 15 2003

approved