A379560 a(1) = 1, a(2) = 4; for n > 2, a(n) is the smallest unused positive nonsquarefree number that shares a factor with a(n-1).

1, 4, 8, 12, 9, 18, 16, 20, 24, 27, 36, 28, 32, 40, 25, 45, 48, 44, 50, 52, 54, 56, 49, 63, 60, 64, 68, 72, 75, 80, 76, 84, 81, 90, 88, 92, 96, 98, 100, 104, 108, 99, 117, 120, 112, 116, 124, 126, 128, 132, 121, 176, 136, 140, 125, 135, 144, 147, 150, 148, 152, 156, 153, 162, 160, 164, 168, 171, 180, 172, 184, 188, 192, 189, 175, 196, 198, 200, 204, 207, 216

Offset

1,2

Links

Scott R. Shannon, Table of n, a(n) for n = 1..10000

Example

a(3) = 8 as a(2) = 4 and 8 is the smallest unused nonsquarefree number (8 = 2^3) that shares a factor with 4.

Crossrefs

Cf. A013929, A100113, A064413, A379248.

Sequence in context: A251756 A357803 A158457 * A072905 A086481 A329507

Adjacent sequences: A379557 A379558 A379559 * A379561 A379562 A379563

Keyword

nonn

Author

Scott R. Shannon, Dec 26 2024

Status

approved