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 A331971 #9 Feb 04 2020 03:57:04
%S A331971 0,0,0,0,1,1,2,1,2,2,2,2,2,2,2,3,1,2,1,3,2,3,1,3,1,3,2,4,1,6,1,4,2,4,
%T A331971 2,5,0,3,1,4,2,5,1,4,2,4,1,6,2,5,2,5,2,8,1,6,1,4,2,7,1,5,3,5,2,8,0,5,
%U A331971 1,6,1,8,2,5,3,6,3,9,0,6,2,5,1,9,1,7,1
%N A331971 a(n) is the number of values of m such that the sum of proper bi-unitary divisors of m (A331970) is n.
%C A331971 The bi-unitary version of A048138.
%C A331971 The offset is 2 as in A048138 since there are infinitely many numbers k (the primes and squares of primes) for which A331970(k) = 1.
%H A331971 Amiram Eldar, <a href="/A331971/b331971.txt">Table of n, a(n) for n = 2..30000</a>
%e A331971 a(8) = 2 since 8 is the sum of the proper bi-unitary divisors of 2 numbers: 10 (1 + 2 + 5) and 12 (1 + 3 + 4).
%t A331971 fun[p_, e_] := If[OddQ[e], (p^(e + 1) - 1)/(p - 1), (p^(e + 1) - 1)/(p - 1) - p^(e/2)]; bsigma[1] = 1; bsigma[n_] := Times @@ (fun @@@ FactorInteger[n]); bs[n_] := bsigma[n] - n; m = 300; v = Table[0, {m}]; Do[b = bs[k]; If[2 <= b <= m, v[[b]]++], {k, 1, m^2}]; Rest @ v
%Y A331971 Cf. A048138, A188999, A222266, A324938, A331970, A331973.
%K A331971 nonn
%O A331971 2,7
%A A331971 _Amiram Eldar_, Feb 03 2020