# How to making a repeting list out of tables?

I'm a little bit trouble with the below task, I'd like to make a repeting list out of a table. This is the starting point for the list

And I like to make them into this form:

How should I make this? Thank you very much for the answers in advance too!

E.g:

S = Table[{Subscript[α, i], Subscript[μ, i]}, {i, 5}];
FoldList[Join, S]

arr = Array[{Subscript[a, #], Subscript[m, #]} &, 5]
Catenate /@ (Take[arr, #] &) /@ Range[5]


You can do this in many ways. For example:

Join @@@ Table[{Subscript[α, i], Subscript[μ, i]}, {j,  5}, {i,  j}]


{{Subscript[α, 1], Subscript[μ, 1]},
{Subscript[α, 1], Subscript[μ, 1], Subscript[α, 2], Subscript[μ, 2]},
{Subscript[α, 1], Subscript[μ, 1], Subscript[α, 2], Subscript[μ, 2], Subscript[α, 3], Subscript[μ, 3]},
{Subscript[α, 1], Subscript[μ, 1], Subscript[α, 2], Subscript[μ, 2], Subscript[α, 3], Subscript[μ, 3], Subscript[α, 4], Subscript[μ, 4]},
{Subscript[α, 1], Subscript[μ, 1], Subscript[α, 2], Subscript[μ, 2], Subscript[α, 3], Subscript[μ, 3], Subscript[α, 4], Subscript[μ, 4], Subscript[α, 5], Subscript[μ, 5]}}

TeXForm @ %


$$\scriptsize\left\{\left\{\alpha _1,\mu _1\right\},\left\{\alpha _1,\mu _1,\alpha _2,\mu _2\right\},\left\{\alpha _1,\mu _1,\alpha _2,\mu _2,\alpha _3,\mu _3\right\},\left\{\alpha _1,\mu _1,\alpha _2,\mu _2,\alpha _3,\mu _3,\alpha _4,\mu _4\right\},\left\{\alpha _1,\mu _1,\alpha _2,\mu _2,\alpha _3,\mu _3,\alpha _4,\mu _4,\alpha _5,\mu _5\right\}\right\}$$

Alternatively, you can use:

Flatten[Take[Table[{Subscript[α, i], Subscript[μ, i]}, {i, 5}], #]] & /@ Range[5]

Table[Flatten[{Subscript[α, #], Subscript[μ, #]} & /@ Range[i]], {i, 5}]


same result