<head>array fill</head> <body> <script> let i = 0; const arr = []; let x = 1; let n = +prompt("введите кол-во членов прогрессии N"); for (; i < n; i++) { x = x + 3; arr.push(x); } result = ((2 * 1) + 3 * (n - 1)) / 2 * n; alert(result); </script> </body>
