Arthashastra
तेषाम् एक योगाश् चत्वारस् त्रि योगाश् च, द्वि योगाः षट् एकश् चतुर् योगः ॥
Of these, the single means as well as the combination of any three means are four; the combinations of any two means are six; and the combination of all the four is one.
english translation
teSAm eka yogAz catvAras tri yogAz ca, dvi yogAH SaT ekaz catur yogaH ॥
hk transliteration by Sanscript