A340791 Irregular triangle read by rows in which row n lists the positive divisors of n that are >= sqrt(n) in decreasing order.

1, 2, 3, 4, 2, 5, 6, 3, 7, 8, 4, 9, 3, 10, 5, 11, 12, 6, 4, 13, 14, 7, 15, 5, 16, 8, 4, 17, 18, 9, 6, 19, 20, 10, 5, 21, 7, 22, 11, 23, 24, 12, 8, 6, 25, 5, 26, 13, 27, 9, 28, 14, 7, 29, 30, 15, 10, 6, 31, 32, 16, 8, 33, 11, 34, 17, 35, 7, 36, 18, 12, 9, 6, 37, 38, 19

Offset: 1

Author

Charles Kusniec, Jan 21 2021

Keywords

• nonn
• tabf

Comments

Reversing rows gives A161908.

Examples

			Triangle begins:
   1
   2
   3
   4  2
   5
   6  3
   7
   8  4
   9  3
  10  5
  11
  12  6  4
  13
  14  7
  15  5
  16  8  4
  17
  18  9  6
  19
  20 10  5
  21  7
  22 11
  23
  24 12  8  6
		

Crossrefs

Cf. A038548 (row widths), A160180 (second column), A161908 (rows reversed), A340792.

Programs

PARI

row(n) = Vecrev(select(x->(x>=sqrt(n)), divisors(n))); \\ Michel Marcus, Jan 22 2021