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What is the explicit function for 4,12,24,40,60

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4, 12, 24, 40, 60
4
4 + 8 = 12
12 + 12 = 24
24 + 16 = 40
40 + 20 = 60
For each term n, take the term before
it, add 4n.

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do u mean a pattern?

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what is the rule for this sequence?:)
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look at 1,3,6,10,15 ...here
1+2=3
3+3=6
6+4=10
10+5=15
u get the term by adding 1,2,3,4 & so on to the previous term.
the sequene u gave is obtained by multiplying each term of the above sequence by 4.
And this was a good one.if u get anymore puzzles like this pls share.. i luv em
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comment em here.... :)
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If you do it your way you'd get
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4, 16, 48, 192, 768.
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how? i told 2 multiply each term of 1,3,6,10,15... by 4 getting 4,12,24,40,60...
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i knew people would get ur pattern also ; since muliplication is distributive.
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You're right too. I can't believe I didn't see that.
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That's great thank you!! But, What would the equation be if I wanted to plug in the 127th term?
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ok here it is
for simpleness consider 1,3,6,10,..
let tn be the nth term.
t1=1
t2=t1+2=1+2
t3=t2+3=(1+2)+3
t4=t3+4=1+2+3+4
.......
tn=1+2+3+...+n
=n*(n+1)/2
So in YOUR sequence, tn=4*(tn of my sequence 1,3,6,..)
=4*n(n+1)/2
=2n*(n+1)
Thus 127th term = 2*127*128/2
=16256.
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Wow!
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thanks! :D
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a sub n= a sub (n-1) + 4n

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