Adding column to existing table with specific changing names

Question

I would like to use content of cell A1, A6, A12 to be added as a column next to the existing numbers. I have over 40K of similar rows. Please see example below.

FROM (original table):

Subject:table 1
A1      B1      C1      D1      E1
A2      B2      C2      D2      E2
A3      B3      C3      D3      E3
A4      B4      C4      D4      E4
Subject:table2
A5      B5      C5      D5      E5
A6      B6      C6      D6      E6
A7      B7      C7      D7      E7
A8      B8      C8      D8      E8
A9      B9      C9      D9      E9
Subject:table3
A10     B10     C10     D10     E10
A11     B11     C11     D11     E11
A12     B12     C12     D12     E12
A13     B13     C13     D13     E13
A14     B14     C14     D14     E14

To ( I would like the table to look like this):

Subject:table 1
A1      B1      C1      D1      E1      Subject:table 1
A2      B2      C2      D2      E2      Subject:table 1
A3      B3      C3      D3      E3      Subject:table 1
A4      B4      C4      D4      E4      Subject:table 1
Subject:table2
A5      B5      C5      D5      E5      Subject:table2
A6      B6      C6      D6      E6      Subject:table2
A7      B7      C7      D7      E7      Subject:table2
A8      B8      C8      D8      E8      Subject:table2
A9      B9      C9      D9      E9      Subject:table2
Subject:table3
A10     B10     C10     D10     E10     Subject:table3
A11     B11     C11     D11     E11     Subject:table3
A12     B12     C12     D12     E12     Subject:table3
A13     B13     C13     D13     E13     Subject:table3
A14     B14     C14     D14     E14     Subject:table3

Answer 1

Assuming the results are to go in column F from row 2 downwards, perhaps

=IF(E2="","",if(E1="",A1,F1))

and copy down as far as necessary