This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A088006 #21 Feb 16 2025 05:39:53
%S A088006 -2,-5,-2,3,2,-19,19,-41,-7,-41,17,2,-109,-2,7,-47,-271,199,-127,71,2,
%T A088006 -37,499,2,-71,199,353,-811,1021,-929,59,-457,-449,-163,-683,-157,41,
%U A088006 -751,251,2,-2161,-19,401,467,-61,967,-631,-3659,-2777,3391,-4421,269,-2333,-1201,-4969,4999,-1103,-2647,-1097,269
%N A088006 Abundance values of numbers whose abundance is (+-1) times a prime.
%H A088006 Amiram Eldar, <a href="/A088006/b088006.txt">Table of n, a(n) for n = 1..10000</a>
%F A088006 Solutions x to sigma(k) - 2k = x where abs(x) is a prime number.
%F A088006 a(n) = A033880(A088005(n)). - _Amiram Eldar_, Feb 16 2025
%e A088006 For n = 4: A088005(4) = 18, sigma(18) = 18 + 9 + 6 + 3 + 2 + 1 = 39, 2*18 = 36, abundance = 39 - 36 = 3 = a(4).
%e A088006 For n = 6: A088005(6) = 25, sigma(25)_= 25 + 5 + 1 = 31, 2*25 = 50, abundance = 31 - 50 = -19 = a(6).
%t A088006 ab[x_] := DivisorSigma[1, x]-2*x Do[If[PrimeQ[s=ab[n]], Print[s]], {n, 1, 10000}]
%t A088006 Select[Table[DivisorSigma[1,n]-2n,{n,7000}],PrimeQ[Abs[#]]&] (* _Harvey P. Dale_, Aug 21 2011 *)
%o A088006 (PARI) list(lim) = {my(ab); for(k = 1, lim, ab = sigma(k) - 2*k; if(isprime(abs(ab)), print1(ab, ", ")));} \\ _Amiram Eldar_, Feb 16 2025
%Y A088006 Cf. A000040, A000203, A033880, A077374, A087998, A088005.
%K A088006 sign
%O A088006 1,1
%A A088006 _Labos Elemer_, Oct 18 2003