A270571 Numbers with at least one arithmetic progression of four consecutive divisors.

12, 24, 36, 48, 60, 72, 84, 96, 105, 108, 120, 132, 144, 156, 168, 180, 192, 204, 216, 228, 240, 252, 264, 276, 288, 300, 312, 315, 324, 336, 348, 360, 372, 384, 396, 408, 420, 432, 444, 456, 468, 480, 492, 504, 516, 525, 528, 540, 552, 564, 576, 588, 600

Offset: 1

Author

Reinhard Zumkeller, Mar 19 2016

Keywords

• nonn

Comments

Contrast A094529 where the divisors in arithmetic progression do not have to be consecutive.

Examples

			348 is included because its divisors are 1, 2, 3, 4, 6, 12, 29, 58, 87, 116, 174, and 348, and the first four are in arithmetic progression.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A091011, A094529, A094530.

Programs

Mathematica

ap4dQ[n_]:=Count[Partition[Divisors[n],4,1],_?(Length[ Union[ Differences[ #]]] == 1&)]>0; Select[ Range[700],ap4dQ]

Extensions

Edited by Harvey P. Dale and Alois P. Heinz, Mar 19 2016