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The diagram illustrates the formula: 1 + 3 + 5 + ... + (2n - 1) = n² Use the diagram to show that any odd number is the difference of two squares.
Show that 8778, 10296 and 13530 are three triangular numbers and that they form a Pythagorean triple.
Take a triangular number, multiply it by 8 and add 1. What is special about your answer? Can you prove it?