a1=1*2 2 factori
a2=2*3*4 3 factori
a3=4*5*6*7 4 factori
a4=7*8*9*10*11 5 fracori
a5=11*12*13*14*15*16 6 factori
a6=16*17*18*19*20*21*22 7 factori
a7=22*23*24*25*26*27*28*29 8 factori
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presupunem
an= ((n(n-1)/2) +1)* ((n(n-1)/2 +2)*.......*((n(n+1)/2 +1)....n+1 factori
formula ar trebui verificata prin inductie, dar, cum suntem la clasa aIV (????!!!!????), sarim
deci a20=191*192*......*211 ...adica 211-191+1= 21 factori
iar ultimul tremen al sumei fiind
4951*4952*...*5051 inseamnac a are5051-4951+1=101 factori, deci este al 100-lea tremen
deci suma are 100 de termeni
