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Numbers such that all differences between distinct divisors occur exactly once.
4

%I #12 Aug 10 2015 14:48:29

%S 1,2,3,4,5,7,8,9,10,11,13,14,16,17,19,21,22,23,25,26,27,29,31,32,33,

%T 34,35,37,38,39,41,43,44,46,47,49,50,51,52,53,55,57,58,59,61,62,64,65,

%U 67,68,69,71,73,74,76,77,79,81,82,83,85,86,87,89,92,93,94,95,97,98,101,103

%N Numbers such that all differences between distinct divisors occur exactly once.

%C A129510(a(n)) = A066446(a(n)).

%C a(n) = A174905(n) for n<27, A174905(27)=37 whereas a(27)=35. - _Reinhard Zumkeller_, Apr 01 2010

%H Reinhard Zumkeller, <a href="/A129511/b129511.txt">Table of n, a(n) for n = 1..10000</a>

%e See example for a(33)=44 in A129510.

%o (Haskell)

%o import Data.List.Ordered (isect, union)

%o a129511 n = a129511_list !! (n-1)

%o a129511_list = filter (f [] . a027750_row') [1..] where

%o f _ [_] = True

%o f zs (d:ds) = null (dds `isect` zs) && f (dds `union` zs) ds

%o where dds = map (subtract d) ds

%o -- _Reinhard Zumkeller_, Jun 25 2015

%Y Cf. A027750, A066446, A129510, A129512 (complement), A174905.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Apr 19 2007