A370925 Rectangular array, read by antidiagonals: row n consists of the numbers m whose ternary representation starts with 2 and has exactly n runs.

2, 8, 6, 26, 7, 19, 80, 18, 20, 57, 242, 22, 21, 59, 172, 728, 24, 23, 60, 173, 516, 2186, 25, 55, 61, 177, 518, 1549, 6560, 54, 56, 64, 178, 519, 1550, 4647, 19682, 67, 58, 65, 181, 520, 1554, 4649, 13942

Offset: 1

Author

Clark Kimberling, Mar 13 2024

Keywords

• nonn
• base
• tabl

Comments

Every positive integer occurs in this array or A370924.

Examples

			Corner:
       2     8    26    80   242   728  2186
       6     7    18    22    24    25    54
      19    20    21    23    55    56    58
      57    59    60    61    64    65    69
     172   173   177   178   181   182   183
     516   518   519   520   532   533   534
    1549  1550  1554  1555  1558  1559  1560
		

Crossrefs

Cf. A007089, A157671, A370893, A370924.

Programs

Mathematica

d[n_] := First[IntegerDigits[n, 3]];
a[n_] := a[n] = Select[Range[30000],
d[#] == 2 && Length[Split[IntegerDigits[#, 3]]] == n &];
t[n_, k_] := a[n][[k]];
Grid[Table[t[n, k], {n, 1, 10}, {k, 1, 10}]] (* array *)
Table[t[n - k + 1, k], {n, 10}, {k, n, 1, -1}] // Flatten (* sequence *)