const length = 50;

let solutions = new Array(length + 1).fill(-1);

​

function setup() {

  const solution = getLength(length,minblocksize);

  console.log(`The solution is ${solution}`);

}

​

function getLength(space,minblocksize){

  // input: current space and minblock size

  console.log(`space = ${space}`)

  // reached the end

  if (space == 0){

    return 1;

  }

  // potential optimization is to save results and not double compute

  if (solutions[space] != -1){

    return solutions[space];

  }

  // leave the next cell black

  let result = getLength(space - 1,minblocksize);

  // otherwise turn it red

  for(let block = minblocksize; block <= space; block++){

    // insert the block

   let next = space - block;

    if (next > 0) {

      result += getLength(next-1, minblocksize);

    }

  }

  solutions[space] = result;

  console.log(`Setting solutions[${space}] = ${result}`);

  return result;

}