A139718 A number n is included if |k -n/k| divides n for at least one divisor k of n.

2, 6, 8, 12, 18, 20, 24, 30, 32, 36, 42, 48, 50, 54, 56, 60, 72, 80, 90, 96, 98, 108, 110, 120, 128, 132, 140, 144, 150, 156, 162, 168, 180, 182, 192, 200, 210, 216, 224, 240, 242, 252, 270, 272, 288, 294, 300, 306, 320, 324, 336, 338, 342, 350, 360, 378, 380

Offset

1,1

Comments

All terms are even. All positive integers of the form n(n+1) are included.

Links

Alexis Olson, Table of n, a(n) for n = 1..526

Example

36 is included because 3 is a divisor of 36 and |3 - 36/3| = 9 divides 36.

Mathematica

Contribution from Alexis Olson (AlexisOlson(AT)gmail.com), Nov 14 2008: (Start)
For[n = 1; s = {}, n <= 10000, n++,
..For[i = 1, i <= Length[Divisors[n]], i++, k = Divisors[n][[i]];
....If[Abs[k-n/k]>0&&Mod[n, Abs[k-n/k]==0, s=Union[s, {n}]; Break[]]]]; s (End)
odkQ[n_]:=Module[{d=Divisors[n], nz}, nz=#-n/#&/@d; MemberQ[Divisible[ n, Abs[Select[nz, #!=0&]]], True]]; Select[Range[400], odkQ] (* Harvey P. Dale, May 06 2012 *)

Crossrefs

Cf. A139719.

Sequence in context: A077561 A008407 A111224 * A173340 A135311 A200568

Adjacent sequences: A139715 A139716 A139717 * A139719 A139720 A139721

Keyword

nonn

Author

Leroy Quet, May 01 2008

Extensions

More terms from Alexis Olson (AlexisOlson(AT)gmail.com), Nov 14 2008

Status

approved