A134000 Array read by antidiagonals: row n contains the positive integers each with exactly n positive "non-isolated divisors". A divisor, k, of n is non-isolated if (k-1) or (k+1) also divides n.

2, 6, 4, 12, 18, 8, 30, 20, 54, 10, 60, 42, 24, 66, 14, 90, 72, 126, 36, 78, 16, 180, 168, 84, 150, 40, 102, 22, 360, 210, 270, 120, 294, 48, 114, 26, 630, 660, 240, 330, 132, 306, 56, 138, 28, 420, 924, 1080, 480, 336, 144, 342, 80, 162, 32, 840, 720, 1200, 1092, 504

Offset

2,1

Comments

The left column (column 1) of the array is sequence A133996. This array written as a sequence is a permutation of the even positive integers. The array starts at column 1 and row 2. (There are no integers with exactly 1 non-isolated divisor.)

Links

Table of n, a(n) for n=2..61.

Example

2 non-isolated divisors: 2, 4, 8, 10, 14, ...
3 non-isolated divisors: 6, 18, 54, 66, ...
4 non-isolated divisors: 12, 20, 24, ...
etc.

Crossrefs

Cf. A134001, A133996.

Sequence in context: A145177 A007517 A072946 * A127730 A118416 A046204

Adjacent sequences: A133997 A133998 A133999 * A134001 A134002 A134003

Keyword

nonn,tabl

Author

Leroy Quet, Oct 01 2007

Extensions

Extended by Ray Chandler, Jun 25 2008

Status

approved