In bash (and also shell which support brace expansion), you can do:

printf '%s\n' "$(printf 'mytext%s\n\n' {1..71})" | paste -sd', ' - >out

In POSIX shell:

printf '%s\n' "$(
n=1
while [ "$n" -le 71 ]; do
  printf 'mytext%s\n\n' "$n"
  n=$((n+1))
done
)" | paste -sd', ' - >out

In bash (and also shell which support brace expansion), you can do:

printf '%s\n' "$(printf 'mytext%s\n\n' {1..71})" | paste -sd', ' - >out

In POSIX shell:

printf '%s\n' "$(
n=1
while [ "$n" -le 71 ]; do
  printf 'mytext%s\n\n' "$n"
  n=$((n+1))
done
)" | paste -sd', ' - >out

In bash (and also shell which support brace expansion), you can do:

printf '%s\n' "$(printf 'mytext%s\n\n' {1..71})" | paste -sd', ' -

In POSIX shell:

printf '%s\n' "$(
n=1
while [ "$n" -le 71 ]; do
  printf 'mytext%s\n\n' "$n"
  n=$((n+1))
done
)" | paste -sd', '

In bash (and also shell which support brace expansion), you can do:

printf '%s\n' "$(printf 'mytext%s\n\n' {1..71})" | paste -sd', ' - >out

In POSIX shell:

printf '%s\n' "$(
n=1
while [ "$n" -le 71 ]; do
  printf 'mytext%s\n\n' "$n"
  n=$((n+1))
done
)" | paste -sd', ' - >out