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A088723 Numbers having at least one divisor d>1 such that also d+1 is a divisor. 9
6, 12, 18, 20, 24, 30, 36, 40, 42, 48, 54, 56, 60, 66, 72, 78, 80, 84, 90, 96, 100, 102, 108, 110, 112, 114, 120, 126, 132, 138, 140, 144, 150, 156, 160, 162, 168, 174, 180, 182, 186, 192, 198, 200, 204, 210, 216, 220, 222, 224, 228, 234, 240, 246, 252, 258, 260 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A088722(a(n))>0; complement of A088725.

Complement of A132895 relative to A005843, the even numbers. - Chandler

LINKS

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

MATHEMATICA

Select[Range[300], MemberQ[Differences[Select[Divisors[#], #>1&]], 1]&]  (* Harvey P. Dale, Apr 03 2011 *)

PROG

(Haskell)

a088723 n = a088723_list !! (n-1)

a088723_list = filter f [2..] where

   f x = 1 `elem` (zipWith (-) (tail divs) divs)

         where divs = tail $ a027750_row x

-- Reinhard Zumkeller, Dec 16 2013

CROSSREFS

Cf. A088722, A088724, A088725, A088726.

Cf. A027750, A008588 (subsequence).

Sequence in context: A100715 A205525 A094519 * A228870 A291022 A316221

Adjacent sequences:  A088720 A088721 A088722 * A088724 A088725 A088726

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Oct 12 2003

EXTENSIONS

Extended by Ray Chandler, May 29 2008

STATUS

approved

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Last modified July 22 00:57 EDT 2018. Contains 312889 sequences. (Running on oeis4.)