find the nth heptagonal number in typescript

To find the nth heptagonal number, we can use the formula: Hn = n(5n-3)/2.

We can create a function in TypeScript that takes in a number n and returns the nth heptagonal number using this formula:

index.ts
function findNthHeptagonalNumber(n: number): number {
  return n * (5 * n - 3) / 2;
}
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Here's an example usage of this function:

index.ts
const nthHeptagonalNumber = findNthHeptagonalNumber(6); // returns 135
console.log(nthHeptagonalNumber);
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In this example, findNthHeptagonalNumber is called with the argument 6, which corresponds to the sixth heptagonal number. The function returns the value 135, which is the sixth heptagonal number.