sheet1 row with spaces between cells, pulled to sheet2 column with no spaces between cells

i've found this equation
=IFERROR(INDEX(Sheet1!$A$1:$Z$1,SMALL(INDEX(Sheet1!$A$1:$Z$1<>"",0)*COLUMN(Sheet1!$A$1:$Z$1),COLUMN(Sheet1!A$1)+COUNTBLANK(Sheet1!$A$1:$Z$1))),"")
and that lets me pull data from the row on sheet1 to sheet2, excluding all the empty cells.
i however just need every third cell pulled from the row on sheet1 to be put into the column on sheet2.
using equations like this
=IF(MOD(COLUMN(A1),4)=1, INDEX(Main!$A3:$A998, CEILING(COLUMN(A1)/4, 1)),"")
allowed me to pull info from a column on one sheet to a row on another while leaving four blanks inbetween the next data entry
i guess what i need is this reversed.
ceiling and floor functions seem to pertain to rounding so i'm not sure how that works here but it definietly does.
i tried switching columns to rows and such and no luck obviously.
any insight is greatly appreicated. thanks

sheet1 starting cell is m13 (row)
sheet2 starting cell is am3 (column)

info needs to come from sheet1 to sheet2

sheet1 m13 = sheet2 am3
sheet1 p13 = sheet2 am4
sheet1 s13 = sheet2 am5
sheet1 v13 = sheet2 am6

thanks!

Thanks so much man!