2.35.5 Make a sequence or a list : seq $
seq takes two, three, four or five arguments : the first
argument is an expression depending of a parameter (for example j) and
the remaining argument(s) describe which values of j will be used to
generate the sequence. More precisely j is assumed to move
from a to b:

with a default step of 1 or 1: j=a..b or
j,a..b (Maplelike syntax), j,a,b (TIlike syntax)
 or with a specific step:
j=a..b,p (Maplelike syntax), j,a,b,p (TIlike syntax).
If the Maplelike syntax is used, seq returns a sequence,
if the TIlike syntax is used, seq returns a list.
$ is the infixed version of seq when seq has only two
arguments and returns always a sequence.
Remark:

In Xcas mode, the precedence of $ is not the same as
for example in Maple, in case of doubt
put the arguments of $ in parenthesis.
For example, the equivalent of seq(j
^
2,j=1..3) is
(j^
2)$(j=1..3) and
returns (1,0,1,4,9).
The equivalent of seq(4,3) is 4$3 and returns
(4,4,4).
 With Maple syntax, j,a..b,p is not valid.
To specify a step p for the variation of
j from a to b, use j=a..b,p or use the TI syntax
j,a,b,p and get the sequence from the list with op(...).
In summary, the different way to build a sequence are :

with Maplelike syntax

seq has two arguments
either an expression depending of a parameter
(for example j) and j=a..b where a and b are reals,
or a constant expression and an integer n.
seq returns the sequence where j is replaced in the
expression by a, a+1,...,b if b>a and by a, a−1,...,b if b<a,
or seq returns the sequence made by copying n times the constant.
 seq has three arguments an expression depending of a parameter
(for example j) and j=a..b,p where a, b are reals and p is a
real number.
seq returns the sequence where j is replaced in the
expression by a, a+p,...,b if b>a and by a, a−p,...,b
if b<a.
Note that j,a..b is also valid but j,a..b,p is not valid.
 TI syntax

seq has four arguments an expression depending of a parameter (for
example j), the name of the parameter (for example j), a and b where
a and b are reals.
seq returns the list where j is replaced in the
expression by a, a+1,...,b if b>a and by a, a−1,...,b if b<a.
 seq has five arguments an expression depending of a parameter (for
example j), the name of the parameter (for example j), a, b and p
where a, b and p are reals.
seq returns the list where
j is substitued in the
expression by a, a+p,...,a+k*p (a+k*p ≤ b <a+(k+1)*p or
a+k*p ≥ b> a+(k+1)*p).
By default, p=1 if b>a and p=1 if b<a.
Note that
in Maple syntax, seq takes no more than 3 arguments and
returns a sequence
as in TI syntax, seq takes at least 4 arguments
and returns a list.
Input to have a sequence with same elements :
seq(t,4)
Or :
seq(t,k=1..4)
Or :
t$4
Output :
(t,t,t,t)
Input to have a sequence :
seq(j^
3,j=1..4)
Or :
(j^
3)$(j=1..4)
Or :
seq(j^
3,j,1..4)
Output :
(1,4,9,16)
Input to have a sequence :
seq(j^
3,j=1..4,2)
Output :
(1,1,9)
Or to have a list,
Input :
seq(j^
3,j,1,4)
Output :
[1,4,9,16]
Input :
seq(j^
3,j,0,5,2)
Output :
[0,8,64]
Input :
seq(j^
3,j,5,0,2)
or
seq(j^
3,j,5,0,2)
Output :
[125,27,1]
Input :
seq(j^
3,j,1,3,0.5)
Output :
[1,3.375,8,15.625,27]
Input :
seq(j^
3,j,1,3,1/2)
Output :
[1,27/8,8,125/8,27]
Examples

Find the third derivative of ln(t), input:
diff(log(t),t$3)
Output :
(((2*t))/t^
4)
 Input :
l:=[[2,3],[5,1],[7,2]]
seq((l[k][0])$(l[k][1]),k=0 .. size(l)1)
Output :
2,2,2,seq[5],7,7
then eval(ans()) returns:
2,2,2,5,7,7
 Input to transform a string into the list of its characters :
f(chn):={
local l;
l:=size(chn);
return seq(chn[j],j,0,l1);
}
then input:
f("abracadabra")
Output :
["a","b","r","a","c","a","d","a","b","r","a"]