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A362825 Number of ordered triples of involutions on [n] that pairwise commute. 3
1, 1, 8, 22, 232, 1016, 12496, 73648, 1032032, 7586272, 118141696, 1033672256, 17668427008, 178649596672, 3313667912192, 37898019913216, 756948065453056, 9640771045925888, 205935949714235392, 2885307792776353792, 65568056040976818176 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
Two involutions x,y on [n] commute if x*y = y*x.
LINKS
FORMULA
E.g.f.: exp(x + 7*x^2/2 + 7*x^4/4 + x^8/8).
PROG
(PARI) seq(n) = {Vec(serlaplace(exp(x + 7*x^2/2 + 7*x^4/4 + x^8/8 + O(x*x^n))))}
CROSSREFS
Column k=3 of A362824.
Cf. A362819.
Sequence in context: A131622 A217275 A183308 * A117613 A215740 A304177
KEYWORD
nonn
AUTHOR
Andrew Howroyd, May 06 2023
STATUS
approved

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Last modified July 24 22:37 EDT 2024. Contains 374585 sequences. (Running on oeis4.)