symbolic integer, Why doesn't it work?

I want to find the sum:

I tried finding with symbolic integer

syms n t

evalin(symengine,'assume(n,Type::Integer)');

symsum(exp(-k^2*t),k,1,n-1)

or

syms n t

evalin(symengine,'assume(n,Type::Integer)');

symsum(exp(-k*k*t),k,1,n-1)

I have got the next answer

Answer 1

[Shubham Rawat]

Hi Katalin,

You may try this:

syms  k t
evalin(symengine,'assume(n,Type::Integer)');

n = 3; %taking input from workspace
symsum(exp(-k*k*t),k,1,n-1)

Result :

ans =
 
exp(-t) + exp(-4*t)

Hope this Helps!

[Katalin Kuchinka]

Thanks. But, I want to create a function f(t,n).

I need to find