A322761 Irregular triangle read by rows in which n-th row lists all partitions of n, in graded reverse lexicographic ordering, using a compressed notation.

1, 2, 11, 3, 21, 111, 4, 31, 22, 211, 1111, 5, 41, 32, 311, 221, 2111, 11111, 6, 51, 42, 411, 33, 321, 3111, 222, 2211, 21111, 111111, 7, 61, 52, 511, 43, 421, 4111, 331, 322, 3211, 31111, 2221, 22111, 211111, 1111111

Offset: 1

Author

N. J. A. Sloane, Dec 30 2018

Keywords

• nonn
• look
• tabf
• base
• fini

Comments

Officially this is deprecated, since one cannot distinguish between (for example) parts which are 11 and parts which are 1,1. However, it is in common use and is included for completeness. See A036037, A080577, etc., for uncompressed versions.

Examples

			Triangle begins:
1,
2, 11,
3, 21, 111,
4, 31, 22, 211, 1111,
5, 41, 32, 311, 221, 2111, 11111,
6, 51, 42, 411, 33, 321, 3111, 222, 2211, 21111, 111111,
7, 61, 52, 511, 43, 421, 4111, 331, 322, 3211, 31111, 2221, 22111, 211111, 1111111,
...
...
		

Links

• Alois P. Heinz, Rows n = 1..28, flattened

Crossrefs

Cf. A000041 (number of terms in row n), A036037, A080577.

See also A006128.

First column gives A000027.

Last elements of rows give A000042.

Programs

Maple

b:= (n, i)-> `if`(n=0 or i=1, [cat(1$n)], [map(x->
    cat(i, x), b(n-i, min(n-i, i)))[], b(n, i-1)[]]):
T:= n-> map(parse, b(n$2))[]:
seq(T(n), n=1..10);  # Alois P. Heinz, Dec 30 2018

Mathematica

revlexsort[f_, c_] := OrderedQ[PadRight[{c, f}]];
Table[FromDigits /@ Sort[IntegerPartitions[n], revlexsort], {n, 1, 8}] // Flatten (* Jean-François Alcover, Oct 20 2020, after Gus Wiseman in A080577 *)