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Tedinoz
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You want a formula to solve the recursive formula F(n) = F(n-1) + ((n-1) * 5000)

There may be many ways to solve your question; consider this as one solution.

This answer uses a "custom formula" wa14322603().

  • Enter the formula in a cell and point the input value to a cell containing an integer. The formula will return the value of the recursive formula.

/**
 * Applies the input value to the recursive formula
 *
 * @param {number} input The value to use in the recursion
 * @return The input applies to the recursion.
 * F(0) = 0
 * F(1) = 5000
 * F(n) = F(n-1) + ((n-1) * 5000)
 * @customfunction
 */
function wa14322603(input) {

  // create a temporary array to hold values
  var resultarray=[];
  
  // assign F(0)
  resultarray.push(0);
  
  // assign F(1)
  resultarray.push(5000)
  
  // define the multiplier
  var multiplier = 5000;
  
  if (input===0){
    var result = resultarray[input]
  }
  
  if (input === 1){
    var result = resultarray[input]
  }
  
  if (input>1){

    // calculate the number of tertaions required
    var iterate=input+1;

    for (var i=2; i<iterate;i++){
    
      // calculate f(n-1}
      var fn_1=resultarray.slice(-1);

      // calculate n-1 * multiplier
      var n_1multiplier = (+i-1)*multiplier

      // add f(n-1) and n_1multiplier
      var result = +fn_1+n_1multiplier;
      
      // assign the result to the array
      resultarray.push(result)
 
      }
    }
   
  // return the last value in the array
  return resultarray.slice(-1);
  
}

Example data showing breakdown of calculations

Screenshot

Tedinoz
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