%I #15 Oct 03 2021 15:24:58
%S 1,7,12,15,13,18,28,24,24,31,39,42,32,36,60,31,42,40,56,72,63,48,54,
%T 48,91,60,56,90,96,84,78,72,124,57,93,72,98,120,72,120,80,90,168,96,
%U 104,127,84,144,126,96,144,195,114,124,140,96,168,186,121,126,224,108,132
%N Sum of divisors of nonprime number A018252(n).
%C Also, 1 together with the numbers A073255.
%H Harvey P. Dale, <a href="/A162194/b162194.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = A000203(A018252(n)).
%p with(NumberTheory): seq(`if`(isprime(n), NULL, sigma(n)), n = 1 .. 100); # _Reza K Ghazi_, Aug 28 2021
%t Join[{1},DivisorSigma[1,#]&/@Select[Range[100],CompositeQ]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, May 27 2017 *)
%o (PARI) a = List(); for(n=1, 100, if(!isprime(n), listput(a, sigma(n)))); Vec(a) \\ _Reza K Ghazi_, Aug 28 2021
%o (SageMath) [sigma(n) for n in range(1, 101) if not is_prime(n)] # _Reza K Ghazi_ Aug 28 2021
%Y Cf. A000203, A018252, A073255, A162194, A162195.
%K easy,nonn
%O 1,2
%A _Omar E. Pol_, Jul 04 2009