A088723 Numbers k with at least one divisor d>1 such that d+1 also divides k.

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

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: A324652 A205525 A094519 * A228870 A291022 A348719

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