A115621 Signature of partitions in Abramowitz and Stegun order.

1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 2, 1, 2, 4, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 3, 5, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 3, 1, 3, 2, 2, 1, 4, 6, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 2, 1, 3, 1, 1, 2, 1, 3, 1, 4, 2, 3, 1, 5, 7, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 3, 1, 1, 2, 2, 2, 1, 1, 2

Offset

1,3

Comments

The signature of a multiset is a partition consisting of the repetition factors of the original partition. Regarding a partition as a multiset, the signature of a partition is defined. E.g., [1,1,3,4,4] = [1^2,3^1,4^2], so the repetition factors are 2,1,2, making the signature [1,2,2] = [1,2^2]. Partitions are written here in increasing part size, so [1,2^2] is 1,2,2, not 2,2,1. - Edited by Franklin T. Adams-Watters, Jul 09 2012

The sum (or order) of the signature is the number of parts of the original partition and the number of parts of the signature is the number of distinct parts of the original partition.

Links

Robert Price, Table of n, a(n) for n = 1..8266 (first 20 rows).

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].

Example

[1];
[1], [2];
[1], [1,1], [3];
[1], [1,1], [2], [1,2], [4];
...
From Hartmut F. W. Hoft, Apr 25 2015: (Start)
Extending the triangle to rows 5 and 6 where row headings indicate the number of elements in the underlying partitions. Brackets group the multiplicities of a single partition.
    row 5         row 6
1:  [1]           [1]
2:  [1,1] [1,1]   [1,1] [1,1] [2]
3:  [1,2] [1,2]   [1,2] [1,1,1] [3]
4:  [1,3]         [1,3] [2,2]
5:  [5]           [1,4]
6:                [6]
(End)

Mathematica

(* row[] and triangle[] compute structured rows of the triangle as laid out above *)
mL[pL_] := Map[Last[Transpose[Tally[#]]]&, pL]
row[n_] := Map[Map[Sort, mL[#]]&, GatherBy[Map[Sort, IntegerPartitions[n]], Length]]
triangle[n_] := Map[row, Range[n]]
a115621[n_]:= Flatten[triangle[n]]
Take[a115621[8], 105] (* data *)  (* Hartmut F. W. Hoft, Apr 25 2015 *)
Map[Sort[#, Less] &, Table[Last /@ Transpose /@ Tally /@ Sort[Reverse /@ IntegerPartitions[n]], {n, 8}], 2]

Prog

(SageMath) from collections import Counter
def A115621_row(n):
    h = lambda p: sorted(Counter(p).values())
    return flatten([h(p) for k in (0..n) for p in Partitions(n, length=k)])
for n in (1..10): print(A115621_row(n)) # Peter Luschny, Nov 02 2019

Crossrefs

Cf. A036036, A113787, A115622, A103921 (part counts), A000070 (row counts).

Sequence in context: A224765 A369167 A160267 * A326514 A077565 A316979

Adjacent sequences: A115618 A115619 A115620 * A115622 A115623 A115624

Keyword

nonn,tabf

Author

Franklin T. Adams-Watters, Jan 25 2006

Status

approved