An 
-firecracker
is a graph obtained by the concatenation of 
-stars by linking one leaf from
each (Chen et al. 1997, Gallian 2007).
Firecracker graphs are graceful (Chen et al. 1997, Gallian 2018).
Precomputed properties of firecrackers are implemented in the Wolfram Language as GraphData[
"Firecracker", 
n, k
].
