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A060683 Numbers for which the differences between consecutive divisors (ordered by size) are distinct. 7
1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 16, 17, 19, 21, 22, 23, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 37, 38, 39, 41, 43, 44, 46, 47, 49, 50, 51, 52, 53, 55, 57, 58, 59, 61, 62, 64, 65, 67, 68, 69, 71, 73, 74, 76, 77, 79, 81, 82, 83, 85, 86, 87, 88, 89, 92, 93, 94, 95, 97, 98 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A060682(a(n)) = A000005(a(n)) - 1, n > 1. - Reinhard Zumkeller, Jun 25 2015

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

A. Balog, P. Erdős and G. Tenenbaum, On Arithmetic Functions Involving Consecutive Divisors, In: Analytical Number Theory, pp. 77-90, Birkhauser, Basel, 1990.

EXAMPLE

For n=6, divisors={1,2,3,6}; differences={1,1,3}, which are not distinct, so 6 is not in the sequence.

MATHEMATICA

test[n_ ] := Length[dd=Drop[d=Divisors[n], 1]-Drop[d, -1]]==Length[Union[dd]]; Select[Range[1, 100], test]

PROG

(Haskell)

a060683 n = a060683_list !! (n-1)

a060683_list = 1 : filter (\x -> a060682 x == a000005' x - 1) [2..]

-- Reinhard Zumkeller, Jun 25 2015

CROSSREFS

Cf. A000005, A060680, A060681, A060682, A060765.

Cf. A060682, A259366 (complement).

Sequence in context: A091010 A306528 A116358 * A129511 A174905 A260402

Adjacent sequences:  A060680 A060681 A060682 * A060684 A060685 A060686

KEYWORD

nonn

AUTHOR

Labos Elemer, Apr 19 2001

EXTENSIONS

Edited by Dean Hickerson, Jan 22 2002

STATUS

approved

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Last modified May 25 03:11 EDT 2019. Contains 323539 sequences. (Running on oeis4.)