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A060764 Number of divisors of n which are not also differences between consecutive divisors (ordered by increasing magnitude) of n. 4
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, 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, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

EXAMPLE

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.

MATHEMATICA

a[n_] := Length[Complement[d=Divisors[n], Drop[d, 1]-Drop[d, -1]]]

PROG

(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

CROSSREFS

Cf. A000005, A060741, A060763.

Sequence in context: A301957 A318874 A001227 * A105149 A295894 A068307

Adjacent sequences:  A060761 A060762 A060763 * A060765 A060766 A060767

KEYWORD

nonn

AUTHOR

Labos Elemer, Apr 24 2001

EXTENSIONS

Edited by Dean Hickerson, Jan 22 2002

STATUS

approved

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Last modified October 20 17:24 EDT 2018. Contains 316392 sequences. (Running on oeis4.)