The first pattern needs 7 pieces, the second pattern needs 19 pieces, and the third pattern needs 37 pieces, According to this method, the total number of pieces needed to place the nth pattern is () {hint, the fourth pattern needs 61 pieces; the fifth yuan needs 91 pieces}

The first pattern needs 7 pieces, the second pattern needs 19 pieces, and the third pattern needs 37 pieces, According to this method, the total number of pieces needed to place the nth pattern is () {hint, the fourth pattern needs 61 pieces; the fifth yuan needs 91 pieces}

+If the first graph is 6 × 1 + 1 = 7, the second graph is 6 × 1 + 6 × 2 + 1 = 19, and the third graph is 6 × 1 + 6 × 2 + 6 × 3 + 1 = 37, then the nth graph is 6 × 1 + 6 × 2 + 6 × 3 + ·· + 6 × n + 1 = 6 × (1 + 2 + 3 + ·· + n) + 1 = 6 × n / 2 (1 + n) + 1 = 3N (n + 1) + 1