even static method

List<int> even(
  1. int columns
)

Implementation

static List<int> even(int columns) =>columns > 1 ? List.generate(columns, (c){
  if(c == 0 || c == columns -1 ) return c + 1;
  return (c + 1) % 2 == 0 ? c + 1 : -1;
}).where((i)=>i != -1).toList() : [1];