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

1,2

Comments

Reversing rows gives A161908.

Links

Table of n, a(n) for n=1..76.

Example

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

Prog

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

Crossrefs

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

Sequence in context: A286547 A157000 A026346 * A369422 A361020 A368693

Adjacent sequences: A340788 A340789 A340790 * A340792 A340793 A340794

Keyword

nonn,tabf

Author

Charles Kusniec, Jan 21 2021

Status

approved