The sequence An is defined by A1 2 and An 1 An 2n what is the value of A100

answer is 9902.
A2=A1+2,A3=A1+6 similarly A100=A1+9900
10 years agoHelpfull: Yes(2) No(7)
a2 =a1+1 =a1+2*1=4
a3 =a2+1 = a2+4=8
a4 = a3+1 =a3+6 =14
a5 = a4+1 = a4+8 = 22
......
the diff b/w a1,a2,a3,a4...
2,6,8,10....
diff b/w this is 2,2,2,2....
so it will make quadratic eqn
An=an^2+bn+c
A1=a+b+c=2
A2=4a+2b+c=4
A3=9a+3b+c=8
a=-1
b=1
c=2
then A100=9902
10 years agoHelpfull: Yes(2) No(2)
the last place is filled with 0. then the remaining 6 places can be filled in 6! ways= 720
10 years agoHelpfull: Yes(1) No(7)

The sequence {An} is defined by A1 = 2 and An+1=An+2n what is the value of A100