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 A126131 #16 Oct 11 2017 09:17:02
%S A126131 1,2,1,2,1,3,1,3,2,2,1,5,1,2,2,3,1,4,1,4,2,2,1,6,2,2,2,3,1,5,1,4,2,2,
%T A126131 2,6,1,2,2,5,1,4,1,3,4,2,1,6,1,4,2,3,1,5,2,4,2,2,1,8,1,2,3,4,2,4,1,3,
%U A126131 2,5,1,8,1,2,3,3,2,4,1,6,3,2,1,7,2,2,2,4,1,7,2,3,2,2,2,7,1,3,3,5,1,4,1,4,4
%N A126131 a(n) = number of divisors of n which equal any d(k) for 1 <= k <= n, where d(k) is the number of positive divisors of k.
%H A126131 Michael De Vlieger, <a href="/A126131/b126131.txt">Table of n, a(n) for n = 1..10000</a>
%e A126131 The number of divisors of the integers 1 through 10 form the sequence 1,2,2,3,2,4,2,4,3,4. The divisors of 10 are 1,2,5,10. The divisors of 10 which occur in the sequence of d(k)'s, 1 <= k <= 10, are 1 and 2. So a(10) = 2.
%e A126131 From _Michael De Vlieger_, Oct 10 2017: (Start)
%e A126131 Records and their indices in a(n).
%e A126131 i = index in table
%e A126131 n = index of record r in this sequence
%e A126131 k = index of n in A002182.
%e A126131 MN(n) = rev(A054841(n)) = concatenation of multiplicities of
%e A126131 prime divisors of n, e.g., MN(60) = "211".
%e A126131 r = record in this sequence.
%e A126131 .
%e A126131 i n k MN(n) r
%e A126131 ----------------------------
%e A126131 1 1 1 0 1
%e A126131 2 2 2 1 2
%e A126131 3 6 4 11 3
%e A126131 4 12 5 21 5
%e A126131 5 24 6 31 6
%e A126131 6 60 9 211 8
%e A126131 7 120 10 311 9
%e A126131 8 180 11 221 11
%e A126131 9 240 12 411 12
%e A126131 10 360 13 321 14
%e A126131 11 720 14 421 16
%e A126131 12 1260 16 2211 18
%e A126131 13 1680 17 4111 19
%e A126131 14 2520 18 3211 21
%e A126131 15 3360 5111 22
%e A126131 16 5040 19 4211 26
%e A126131 17 7560 20 3311 28
%e A126131 18 10080 21 5211 30
%e A126131 19 15120 22 4311 33
%e A126131 20 20160 23 6211 34
%e A126131 21 25200 24 4221 35
%e A126131 22 30240 5311 38
%e A126131 23 50400 27 5221 40
%e A126131 24 60480 6311 42
%e A126131 25 75600 4321 43
%e A126131 (End)
%t A126131 f[n_] :=Length@ Select[Divisors[n], MemberQ[Table[Length@ Divisors[k], {k, n}], # ] &];Table[f[n], {n, 105}] (* _Ray Chandler_, Dec 20 2006 *)
%t A126131 Block[{nn = 105, s}, s = DivisorSigma[0, Range@ nn]; Table[DivisorSum[n, 1 &, MemberQ[Take[s, n], #] &], {n, nn}]] (* _Michael De Vlieger_, Oct 10 2017 *)
%o A126131 (PARI) a(n) = #setintersect(divisors(n), Set(vector(n, k, numdiv(k)))); \\ _Michel Marcus_, Oct 11 2017
%Y A126131 Cf. A126132.
%K A126131 nonn
%O A126131 1,2
%A A126131 _Leroy Quet_, Dec 18 2006
%E A126131 Extended by _Ray Chandler_, Dec 20 2006