cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A348114 Irregular triangle read by rows: T(n, k) is the number of chains of subspaces 0 < V_1 < ... < V_r = (F_3)^n, counted up to coordinate permutation, with dimension increments given by (any fixed permutation of) the parts of the k-th partition of n in Abramowitz-Stegun order.

Original entry on oeis.org

1, 1, 3, 1, 5, 15, 1, 8, 16, 49, 154, 1, 11, 39, 126, 288, 964, 3275, 1, 15, 87, 168, 291, 1412, 3600, 4957, 12865, 46400, 168862, 1, 19, 176, 644, 608, 6101, 14001, 38996, 22294, 146064, 418072, 549894, 1586761, 6045724, 23115063, 1, 24, 338, 2348, 4849, 1195, 24329
Offset: 1

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Author

Álvar Ibeas, Oct 01 2021

Keywords

Comments

A permutation on the list of dimension increments does not modify the number of subspace chains.
The length of the enumerated chains is r = len(L), where L is the parameter partition.

Examples

			For L = (1, 1, 1), there are 52 (= 13 * 4) = A347486(3, 3) subspace chains 0 < V_1 < V_2 < (F_3)^3.
The permutations of the three coordinates classify them into 15 = T(3, 3) orbits.
T(3, 2) = 5 refers to partition (2, 1) and counts subspace chains in (F_3)^2 with dimensions (0, 2, 3), i.e. 2-dimensional subspaces. It also counts chains with dimensions (0, 1, 3), i.e. 1-dimensional subspaces.
Triangle begins:
  k:  1  2  3   4   5   6    7
      ------------------------
n=1:  1
n=2:  1  3
n=3:  1  5 15
n=4:  1  8 16  49 154
n=5:  1 11 39 126 288 964 3275
		

Crossrefs

Formula

If the k-th partition of n in A-St is L = (a, n-a), then T(n, k) = A347970(n, a) = A347970(n, n-a).