The sum formula of 2N-1 and 2n + 1 natural numbers

The sum formula of 2N-1 and 2n + 1 natural numbers

The formula of sum of squares of natural numbers is n (n + 1) (2n + 1) / 6, where n is the last natural number. Substituting (5) into (2), the formula of even sum of squares of natural numbers is 2n (n + 1) (2n + 1) / 3, where 2n is the last natural number
By substituting (5) into (3), the odd sum of squares formula of natural number is n (2n-1) (2n + 1) / 3, where 2N-1 is the last natural number