**I have made a number of contributions to the Online Encyclopedia of Integer Sequences (OEIS). Below are descriptions of the sequences; click on them to go to the OEIS.**

Number of quadrilaterals in a triangular matchstick arrangement of side n.

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**I have made a number of contributions to the Online Encyclopedia of Integer Sequences (OEIS). Below are descriptions of the sequences; click on them to go to the OEIS.**

Number of quadrilaterals in a triangular matchstick arrangement of side n.