i need the solutio please

Task3:- We want to generate a function that computes the series starting from 0 and ending until the given number following the sequence: 0136 10 15 21 28 36 45 55 which is created by 0+1+2+3+4+5+6, 0+1+2+3+4+5+6+7 etc.. Input: LastNumber Output: series and result Example: Input: 6 Output: 0+1+2+3+4+5+6 21 Input: -15 Output:-150 Input: 0 Output: 0-0