The 6-polyiamond illustrated above.
Hexagon Polyiamond
See also
HexagonExplore with Wolfram|Alpha
References
Golomb, S. W. Polyominoes: Puzzles, Patterns, Problems, and Packings, 2nd ed. Princeton, NJ: Princeton University Press, p. 92, 1994.Referenced on Wolfram|Alpha
Hexagon PolyiamondCite this as:
Weisstein, Eric W. "Hexagon Polyiamond." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/HexagonPolyiamond.html