211012

Appears in sequences

• Number of convex quadrilaterals, distinct up to congruence, on an n X n grid (or geoboard).at n=12A181944
• Number of 2X4 integer matrices with each row summing to zero, row elements in nondecreasing order, rows in lexicographically nondecreasing order, and the sum of squares of the elements <= 2*n^2 (number of collections of 2 zero-sum 4-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).at n=15A192699
• Numbers that are nontrivially palindromic in three or more consecutive integer bases.at n=35A279093