cp's OEIS Frontend

A060763 Number of distinct differences between consecutive divisors (ordered by increasing magnitude) of n which are not also divisors of n.

%I A060763 #13 Jul 04 2017 04:02:39
%S A060763 0,0,1,0,1,0,1,0,2,1,1,0,1,1,2,0,1,0,1,0,3,1,1,0,2,1,3,1,1,1,1,0,3,1,
%T A060763 3,0,1,1,3,1,1,0,1,1,4,1,1,0,2,2,3,1,1,0,3,2,3,1,1,0,1,1,4,0,3,1,1,1,
%U A060763 3,3,1,0,1,1,3,1,3,1,1,2,4,1,1,1,3,1,3,1,1,1,2,1,3,1,3,0,1,2,4,0,1,1,1,1,5
%N A060763 Number of distinct differences between consecutive divisors (ordered by increasing magnitude) of n which are not also divisors of n.
%H A060763 Robert Israel, <a href="/A060763/b060763.txt">Table of n, a(n) for n = 1..10000</a>
%e A060763 For n=70, divisors={1,2,5,7,10,14,35,70}; differences={1,3,2,3,4,21,35}; the differences {3,4,21} are not divisors, so a(70)=3.
%p A060763 f:= proc(n) local D,L;
%p A060763   D:= numtheory:-divisors(n);
%p A060763   L:= sort(convert(D,list));
%p A060763   nops(convert(L[2..-1]-L[1..-2],set) minus D);
%p A060763 end proc:
%p A060763 map(f, [$1..200]); # _Robert Israel_, Jul 03 2017
%t A060763 a[n_] := Length[Complement[Drop[d=Divisors[n], 1]-Drop[d, -1], d]]
%o A060763 (PARI) a(n) = my(d=divisors(n)); #select(x->(setsearch(d, x)==0), vecsort(vector(#d-1, k, d[k+1] - d[k]),,8)); \\ _Michel Marcus_, Jul 04 2017
%Y A060763 Cf. A060682, A060738, A060764.
%K A060763 nonn
%O A060763 1,9
%A A060763 _Labos Elemer_, Apr 24 2001
%E A060763 Edited by _Dean Hickerson_, Jan 22 2002