If I have a sequence - lets say an algebraic sequence

and a function - really doesn't matter what function as long as it takes some sort of arguments

sequence : [1,3,5,7,9,...]

function : result = x*7 + x - 3

what I am interested in is the following sequence : [result @ 1, result @ 3, result @ 5,result @ 7,result @ 9, ...]

What would the formula be for the sum of the above values

Guest Mar 9, 2021

#1

#3**0 **

my bad for the lacking explanation

I'm bad with words so I'll give an example

say we have the following sequence :

ππ=1+(πβ1)*2

thus ππ=2*π-1

and the following function :

Xπ = ππ^2 + 12 * ππ + 7

thus Xπ = 4*π^2 + 20*π - 4

how do I get the sum of say the first 10 terms :

sum Xn from n = 1 to n = 10

Guest Mar 9, 2021

#2**0 **

my bad for the lacking explanation

I'm bad with words so I'll give an example

say we have the following sequence :

ππ=1+(πβ1)*2

thus ππ=2*π-1

and the following function :

Xπ = ππ^2 + 12 * ππ + 7

thus Xπ = 4*π^2 + 20*π - 4

how do I get the sum of say the first 10 terms :

sum Xn from n = 1 to n = 10

Guest Mar 9, 2021

#4**+1 **

Apologies, I misread your question!

Unfortunately, there is no general rule for arbitrary functions. For some functions you can find an expression for the sum, for others you can't. Do you have some specific functions in mind?

Alan
Mar 9, 2021