%I #27 Apr 06 2024 07:57:25
%S 4,3,2,12,12,19,10,12,28,12,8,48,12,4,51,12,26,56,4,54,60,17,12,2,64,
%T 24,12,120,60,72,12,56,115,72,80,58,39,144,12,20,186,12,124,7,72,65,
%U 96,18,156,168,64,12,56,104,78,264,12,224,12,68,192,180,14,120,160,12,243
%N Abundancy of n-th abundant number: sigma(k) - 2k for k such that this is > 0.
%H Harvey P. Dale, <a href="/A033881/b033881.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = A033880(A005101(n)). - _Amiram Eldar_, Apr 06 2024
%p with(numtheory): for n from 2 to 500 do if sigma(n) - 2*n > 0 then printf(`%d,`, sigma(n) - 2*n) fi: od:
%t Select[Table[DivisorSigma[1,n]-2n,{n,300}],#>0&] (* _Harvey P. Dale_, May 21 2020 *)
%o (PARI) lista(kmax) = {my(ab); for(k = 1, kmax, ab = sigma(k)-2*k; if(ab > 0, print1(ab, ", ")));} \\ _Amiram Eldar_, Apr 06 2024
%Y Cf. A000203, A005101, A033880, A033884.
%K nonn
%O 1,1
%A _N. J. A. Sloane_
%E More terms from _James A. Sellers_, Feb 19 2001