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A060764 Number of divisors of n which are not also differences between consecutive divisors (ordered by increasing magnitude) of n.

%I A060764 #15 Feb 21 2023 11:00:49
%S A060764 1,1,2,1,2,2,2,1,3,2,2,3,2,2,4,1,2,3,2,2,4,2,2,4,3,2,4,2,2,4,2,1,4,2,
%T A060764 4,4,2,2,4,4,2,4,2,2,6,2,2,5,3,3,4,2,2,4,4,4,4,2,2,5,2,2,6,1,4,4,2,2,
%U A060764 4,5,2,6,2,2,6,2,4,4,2,5,5,2,2,7,4,2,4,2,2,6,4,2,4,2,4,6,2,3,6,3,2,4,2,2,8
%N A060764 Number of divisors of n which are not also differences between consecutive divisors (ordered by increasing magnitude) of n.
%H A060764 Antti Karttunen, <a href="/A060764/b060764.txt">Table of n, a(n) for n = 1..65537</a>
%e A060764 For n=70, divisors={1,2,5,7,10,14,35,70}; differences={1,3,2,3,4,21,35}; the divisors {5,7,10,14,70} are not differences, so a(70)=5.
%t A060764 a[n_] := Length[Complement[d=Divisors[n], Drop[d, 1]-Drop[d, -1]]]
%o A060764 (PARI) A060764(n) = { my(divs=divisors(n), diffs=vecsort(vector(#divs-1,i,divs[i+1]-divs[i]), ,8), c=#divs); for(i=1,#diffs,if(!(n%diffs[i]),c--)); (c); }; \\ _Antti Karttunen_, Sep 21 2018
%o A060764 (Python)
%o A060764 from itertools import pairwise
%o A060764 from sympy import divisors
%o A060764 def A060764(n):
%o A060764     e = map(lambda x:x[1]-x[0],pairwise(d:=divisors(n)))
%o A060764     return len(set(d)-set(e)) # _Chai Wah Wu_, Feb 21 2023
%Y A060764 Cf. A000005, A060741, A060763.
%K A060764 nonn
%O A060764 1,3
%A A060764 _Labos Elemer_, Apr 24 2001
%E A060764 Edited by _Dean Hickerson_, Jan 22 2002