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 A083532 #22 Dec 26 2024 03:54:37
%S A083532 3,4,1,1,5,1,2,2,1,1,2,1,1,2,4,1,1,2,4,2,2,1,1,2,1,1,1,1,2,3,1,2,3,1,
%T A083532 1,1,2,1,1,2,2,1,1,2,2,1,1,2,1,1,1,1,3,2,1,2,2,1,1,2,2,1,1,2,2,2,2,1,
%U A083532 1,1,1,3,1,2,4,1,1,3,1,1,1,2,2,1,1,2,1,1,1,1,2,2,1,1,2,2,2,2,2,1,1,2,1,2,1
%N A083532 First difference sequence of A007369. Differences between impossible values for sum of divisors of n.
%H A083532 Amiram Eldar, <a href="/A083532/b083532.txt">Table of n, a(n) for n = 1..10000</a>
%F A083532 a(n) = A007369(n+1) - A007369(n).
%e A083532 29 and 33 are the 15th and 16th nonsense values for sigma(x), since there exist no numbers n of which they are sums of divisors, while {30,31,32} equal sigma(x); e.g., for x = 29, 16, 31, respectively, thus 33 - 29 = 4 = a(15) = A007369(16) - A007369(15).
%t A083532 t0[x_] := Table[j, {j, 1, x}]; t=Table[DivisorSigma[1, w], {w, 1, 25000}]; u=Union[%]; c=Complement[t0[25000], u]; Delete[c-RotateRight[c], 1]
%Y A083532 Cf. A002191, A007369, A083235, A083531, A083533, A083534, A083536.
%K A083532 nonn
%O A083532 1,1
%A A083532 _Labos Elemer_, May 20 2003