A270571 - OEIS

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

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OFFSET

1,1

COMMENTS

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

LINKS

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

EXAMPLE

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.

MATHEMATICA

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

CROSSREFS