A362825 - OEIS

%I #7 May 08 2023 15:33:02

%S 1,1,8,22,232,1016,12496,73648,1032032,7586272,118141696,1033672256,

%T 17668427008,178649596672,3313667912192,37898019913216,

%U 756948065453056,9640771045925888,205935949714235392,2885307792776353792,65568056040976818176

%N Number of ordered triples of involutions on [n] that pairwise commute.

%C Two involutions x,y on [n] commute if x*y = y*x.

%H Andrew Howroyd, <a href="/A362825/b362825.txt">Table of n, a(n) for n = 0..200</a>

%F E.g.f.: exp(x + 7*x^2/2 + 7*x^4/4 + x^8/8).

%o (PARI) seq(n) = {Vec(serlaplace(exp(x + 7*x^2/2 + 7*x^4/4 + x^8/8 + O(x*x^n))))}

%Y Column k=3 of A362824.

%Y Cf. A362819.

%K nonn

%O 0,3

%A _Andrew Howroyd_, May 06 2023