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 A090128 #16 May 27 2024 11:08:24
%S A090128 1,3,4,7,6,12,8,15,13,18,28,14,24,31,39,20,42,32,36,60,40,56,30,72,63,
%T A090128 48,54,91,38,90,96,44,84,78,124,57,93,98,120,80,168,62,104,127,144,68,
%U A090128 126,195,74,114,140,186,121,224,108,132,180,234,112,128,252,171,156,217
%N A090128 Distinct values of sigma(k), the sum of divisors, in order of appearance as k grows.
%C A090128 Constructed by reading A000203 and deleting values that already appeared earlier: A000203(15)=24 is dropped because equal to A000203(14). A000203(17)=18 is dropped because equal to A000203(10) etc. - _R. J. Mathar_, May 27 2024
%H A090128 Giovanni Resta, <a href="/A090128/b090128.txt">Table of n, a(n) for n = 1..10000</a>
%H A090128 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%t A090128 t = Table[DivisorSigma[1, w], {w, 100}]; u = Union[t]; uu = Union@ Table[ Min[ Flatten[ Position[t, u[[j]]]]], {j, Length[u]}]; Table[ t[[uu[[j]]]], {j, Length[uu]}]
%t A090128 DeleteDuplicates[DivisorSigma[1,Range[100]]] (* _Harvey P. Dale_, Dec 01 2018 *)
%Y A090128 Cf. A000203, A002191 (terms in ascending order).
%Y A090128 Cf. A053212, A090127.
%K A090128 nonn,easy
%O A090128 1,2
%A A090128 _Labos Elemer_, Jan 16 2004