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 A195150 #41 Jan 18 2024 02:58:21
%S A195150 0,0,1,1,1,1,1,2,2,2,1,2,1,2,3,3,1,3,1,3,3,2,1,4,2,2,3,4,1,4,1,4,3,2,
%T A195150 3,5,1,2,3,5,1,4,1,4,5,2,1,6,2,4,3,4,1,5,3,5,3,2,1,6,1,2,5,5,3,5,1,4,
%U A195150 3,6,1,7,1,2,5,4,3,5,1,7,4,2,1,7,3,2
%N A195150 Number of divisors d of n such that d-1 does not divide n.
%C A195150 Define "subdivisor" of n to be the positive integer b such that b = d - 1, if d divides n and b does not divide n. For the list of subdivisors of n see A195153.
%C A195150 First occurrence of k is given in A173569. - _Robert G. Wilson v_, Sep 23 2011
%H A195150 Reinhard Zumkeller, <a href="/A195150/b195150.txt">Table of n, a(n) for n = 1..10000</a>
%F A195150 a(n) = A137921(n) - 1. - _Robert G. Wilson v_, Sep 23 2001
%F A195150 Sum_{k=1..n} a(k) ~ n * (log(n) + 2*gamma - 3), where gamma is Euler's constant (A001620). - _Amiram Eldar_, Jan 18 2024
%e A195150 a(24) = 4 since the divisors of 24 are 1,2,3,4,6,8,12,24, so the subdivisors of 24 are 5,7,11,23 because 6-1 = 5, 8-1 = 7, 12-1 = 11 and 24-1 = 23. Note that the positive integers 1,2,3 are not subdivisors of 24 because they are divisors of 24.
%t A195150 f[n_] := Module[{d = Divisors[n]}, Length[Select[Rest[d-1], Mod[n, #] > 0 &]]]; Table[f[n], {n, 100}] (* _T. D. Noe_, Sep 22 2011 *)
%o A195150 (Haskell)
%o A195150 a195150 n = length [d | d <- [3..n], mod n d == 0, mod n (d-1) /= 0]
%o A195150 -- _Reinhard Zumkeller_, Sep 23 2011
%Y A195150 Cf. A000005, A001620, A027750, A066272, A195153, A137921, A173569.
%K A195150 nonn,easy
%O A195150 1,8
%A A195150 _Omar E. Pol_, Sep 19 2011