A374801 Irregular table T(n, k), n > 0, k = 1..A048691(n), read by rows; the n-th row lists the numbers m such that A003990(m) = n.

1, 2, 3, 5, 4, 6, 13, 7, 10, 12, 14, 25, 11, 15, 41, 8, 9, 16, 21, 23, 27, 31, 34, 61, 22, 28, 85, 29, 36, 38, 44, 59, 63, 113, 37, 45, 58, 64, 145, 17, 20, 46, 55, 57, 65, 96, 101, 181, 56, 66, 221, 18, 19, 40, 42, 67, 78, 80, 90, 94, 103, 109, 117, 142, 148, 265, 79, 91, 313

Offset: 1

Author

Rémy Sigrist, Jul 20 2024

Keywords

• nonn
• look
• tabf

Comments

A003990 corresponds to a square array, but we consider it here as a flat sequence (when its values are read according along its antidiagonals).

As a flat sequence this is a permutation of the positive integers with inverse A374802.

Examples

			Triangle T(n, k) begins:
  n   n-th row
  --  ----------------------------------------------------------------
   1  1
   2  2, 3, 5
   3  4, 6, 13
   4  7, 10, 12, 14, 25
   5  11, 15, 41
   6  8, 9, 16, 21, 23, 27, 31, 34, 61
   7  22, 28, 85
   8  29, 36, 38, 44, 59, 63, 113
   9  37, 45, 58, 64, 145
  10  17, 20, 46, 55, 57, 65, 96, 101, 181
  11  56, 66, 221
  12  18, 19, 40, 42, 67, 78, 80, 90, 94, 103, 109, 117, 142, 148, 265
  13  79, 91, 313
  14  30, 35, 92, 105, 107, 119, 197, 204, 365
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10016
• Rémy Sigrist, PARI program
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A003990, A048691, A374802 (inverse).

Programs

PARI

\\ See Links section.