A194551 a(n) is the n-th largest part that are visible in one of the three views of the version "Tree" of the section model of partitions.

1, 2, 3, 4, 5, 3, 6, 4, 7, 5, 4, 8, 3, 6, 5, 9, 4, 7, 6, 5, 10, 5, 4, 8, 7, 6, 11, 3, 6, 5, 9, 4, 8, 7, 6, 12, 4, 7, 6, 5, 10, 5, 9, 8, 7, 13, 5, 4, 8, 7, 6, 11, 6, 5, 10, 9, 8, 7, 14, 3, 6, 5, 9, 4, 8, 7, 6, 12, 7, 6, 11, 5, 10, 9, 8, 15

Offset: 1

Author

Omar E. Pol, Nov 22 2011

Keywords

• nonn

Comments

It appears that if this is written as a triangle (see example) and n >= 3 then row n has the following property:

If n is congruent to 0 (mod 3) then row n converge to the sequence 3,6,5,9,4,8,7,6,12... in which the records are the numbers >= 3 that are congruent to 0 (mod 3).

If n is congruent to 1 (mod 3) then row n converge to the sequence 4,7,6,5,10,5,9,8,7,13... in which the records are the numbers >= 4 that are congruent to 1 (mod 3).

If n is congruent to 2 (mod 3) then row n converge to the sequence 5,4,8,7,6,11,6,5,10,9,8,7,14... in which the records are the numbers >= 5 that are congruent to 2 (mod 3).

For more information see A135010.

Examples

			Written as a triangle begins:
1;
2;
3;
4;
5;
3,6;
4,7;
5,4,8;
3,6,5,9;
4,7,6,5,10;
5,4,8,7,6,11;
3,6,5,9,4,8,7,6,12;
4,7,6,5,10,5,9,8,7,13;
5,4,8,7,6,11,6,5,10,9,8,7,14;
...
Row n has length A008483(n), if n >= 3.
		

Links

• Robert Price, Table of n, a(n) for n = 1..56954, 50 rows.

Crossrefs

Cf. A008483, A135010, A138121, A141285, A182730, A182731, A182732, A182733, A194550.

Programs

Mathematica

Join[{1},Table[Drop[l = Last/@DeleteCases[Sort@PadRight[Reverse /@ Cases[IntegerPartitions[n], x_ /; Last[x] != 1]], x_ /; x == 0, 2], First@FirstPosition[l, n - 2, {0}]], {n, 2, 15}]] // Flatten  (* Robert Price, May 15 2020 *)