A119585 Triangle where n-th row is (1,2,3,...n) arranged first by number of divisors and then numerically (among those integers with the same number of divisors).

1, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 3, 5, 4, 1, 2, 3, 5, 4, 6, 1, 2, 3, 5, 7, 4, 6, 1, 2, 3, 5, 7, 4, 6, 8, 1, 2, 3, 5, 7, 4, 9, 6, 8, 1, 2, 3, 5, 7, 4, 9, 6, 8, 10, 1, 2, 3, 5, 7, 11, 4, 9, 6, 8, 10, 1, 2, 3, 5, 7, 11, 4, 9, 6, 8, 10, 12, 1, 2, 3, 5, 7, 11, 13, 4, 9, 6, 8, 10, 12

Offset

1,3

Links

Table of n, a(n) for n=1..91.

Example

Looking at the 9th row, we want to arrange (1,2,3,4,5,6,7,8,9). 1 has 1 divisor.
(2,3,5,7) each have 2 divisors. (4,9) each have 3 divisors. (6,8) each have 4 divisors. So the 9th row is (1)(2,3,5,7)(4,9)(6,8).

Crossrefs

Sequence in context: A222417 A253573 A229945 * A195097 A329288 A181845

Adjacent sequences: A119582 A119583 A119584 * A119586 A119587 A119588

Keyword

nonn,tabl

Author

Leroy Quet, May 31 2006

Status

approved