A261698 Irregular triangle read by rows in which row n lists the odd divisors of n in the order as follows: the smallest, the largest, the second smallest, the second largest, the third smallest, the third largest, and so on.

1, 1, 1, 3, 1, 1, 5, 1, 3, 1, 7, 1, 1, 9, 3, 1, 5, 1, 11, 1, 3, 1, 13, 1, 7, 1, 15, 3, 5, 1, 1, 17, 1, 9, 3, 1, 19, 1, 5, 1, 21, 3, 7, 1, 11, 1, 23, 1, 3, 1, 25, 5, 1, 13, 1, 27, 3, 9, 1, 7, 1, 29, 1, 15, 3, 5, 1, 31, 1, 1, 33, 3, 11, 1, 17, 1, 35, 5, 7, 1, 9, 3, 1, 37, 1, 19, 1, 39, 3, 13, 1, 5, 1, 41, 1, 21, 3, 7, 1, 43, 1, 11, 1, 45, 3, 15, 5, 9

Offset

1,4

Comments

Also the odd numbers of A210959.

Row lengths give A001227.

Row sums give A000593.

Another version of A182469 from which differs at a(14), or T(9,2).

For a similar version see A261697 from which differs at a(34), or T(18,2).

Links

Table of n, a(n) for n=1..108.

Example

List of divisors of 45 from distinct sequences:
45th row of triangle A182469: 1, 3, 5, 9, 15, 45.
45th row of triangle A261697: 1, 45, 3, 5, 15, 9.
45th row of this triangle...: 1, 45, 3, 15, 5, 9.
Triangle begins:
  1;
  1;
  1,  3;
  1;
  1,  5;
  1,  3;
  1,  7;
  1;
  1,  9,  3;
  1,  5;
  1, 11;
  1,  3;
  1, 13;
  1,  7;
  1, 15,  3,  5;
  1;
  1, 17;
  1,  9,  3;
  1, 19;
  1,  5;
  1, 21,  3,  7;
  ...

Crossrefs

Cf. A000593, A001227, A027750, A182469, A210959, A261697.

Sequence in context: A182469 A329984 A261697 * A124738 A131086 A201669

Adjacent sequences: A261695 A261696 A261697 * A261699 A261700 A261701

Keyword

nonn,tabf

Author

Omar E. Pol, Sep 21 2015

Status

approved