A360937 - OEIS

A360937

Triangle read by rows: T(n, k) is the k-th Lie-Betti number of a wheel graph on n vertices, for n >= 3 and k >= 0.

1, 3, 8, 12, 8, 3, 1, 1, 4, 20, 56, 84, 90, 84, 56, 20, 4, 1, 1, 5, 32, 108, 212, 371, 547, 547, 371, 212, 108, 32, 5, 1, 1, 6, 45, 171, 442, 1081, 2025, 2616, 2722, 2616, 2025, 1081, 442, 171, 45, 6, 1, 1, 7, 60, 258, 842, 2489, 5440, 8855, 12955, 16785, 16785, 12955, 8855, 5440, 2489, 842, 258, 60, 7, 1

(list; graph; refs; listen; history; text; internal format)

OFFSET

3,2

LINKS

Table of n, a(n) for n=3..71.

Marco Aldi and Samuel Bevins, L_oo-algebras and hypergraphs, arXiv:2212.13608 [math.CO], 2022. See page 9.

Meera G. Mainkar, Graphs and two step nilpotent Lie algebras, arXiv:1310.3414 [math.DG], 2013. See page 1.

Eric Weisstein's World of Mathematics, Wheel Graph.

EXAMPLE

Triangle T(n, k) begins:

k=0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

n=3: 1 3 8 12 8 3 1

n=4: 1 4 20 56 84 90 84 56 20 4 1

n=5: 1 5 32 108 212 371 547 547 371 212 108 32 5 1

n=6: 1 6 45 171 442 1081 2025 2616 2722 2616 2025 1081 442 171 45 6 1

...

PROG

(SageMath) # uses[betti_numbers, LieAlgebraFromGraph from A360571]

def A360937_row(n):

return betti_numbers(LieAlgebraFromGraph(graphs.WheelGraph(n)))

for n in range(3, 7): print(A360937_row(n))

CROSSREFS

Cf. A360571 (path graph), A360572 (cycle graph), A088459 (star graph), A360625 (complete graph), A360936 (ladder graph), A361044 (friendship graph).

Sequence in context: A356865 A050391 A360572 * A361044 A288865 A331069

Adjacent sequences: A360934 A360935 A360936 * A360938 A360939 A360940

KEYWORD

nonn,tabf

AUTHOR

Samuel J. Bevins, Feb 26 2023

STATUS

approved