eech 1=arithmetik sequens
I projekt the 99th will hav 99 as first term & hav 99 terms init
sum av NE sequens=n*(start number + last number)/2
n=99
start number=99
last number=start number+(n-1)*stepsize; stepsize=1 heer
last number=2*99=198
start+last=296
n*(start+last)/2=99*148=14,652