function randomIntFromInterval(min: number, max: number): number {
  return Math.floor(Math.random() * (max - min + 1) + min);
}

function start(elements: HTMLDivElement[], allowedIndexList: number[]): void {
  const filteredElements = elements.filter((_, i) => allowedIndexList.includes(i));
  const randomIndex = randomIntFromInterval(0, filteredElements.length - 1);
  const randomElement = filteredElements[randomIndex];
  randomElement.innerHTML = randomIntFromInterval(1, 25).toString();
}

const elements = Array.from(document.querySelectorAll('.someclass')) as HTMLDivElement[];
const allowedIndexList = [1, 3, 5, 6];

start(elements, allowedIndexList);