A355455 Numbers whose fourth smallest divisor is a square.

12, 24, 36, 45, 48, 60, 63, 72, 84, 96, 108, 120, 132, 135, 144, 156, 168, 175, 180, 189, 192, 204, 216, 225, 228, 240, 252, 264, 275, 276, 288, 300, 312, 324, 325, 336, 348, 360, 372, 384, 396, 405, 408, 420, 425, 432, 441, 444, 456, 468, 475, 480, 492, 495, 504, 516, 528, 539, 540, 552, 564, 567, 575, 576, 585

Offset: 1

Author

Antti Karttunen, Jul 02 2022

Keywords

• nonn

Crossrefs

Cf. A000005, A010054, A355454 (characteristic function).

Cf. also A119315.

Programs

PARI

A355454(n) = ((numdiv(n)>3) && issquare(divisors(n)[4]));
isA355455(n) = A355454(n);