420552

Appears in sequences

• Triangle read by rows: numbers of isomers of unbranched a-4-catapolynonagons.at n=55A120650
• Unbranched a-4-catapolynonagons (see Brunvoll reference for precise definition).at n=8A121123
• Sum of positive even numbers up to n^2.at n=35A235367
• Consider any concatenation of the type n = concat(a,b). Sequence lists numbers whose reverses are the sum of the products of some of such couples a and b.at n=22A281555