an vs to

an

prep
  • In each; to or for each; per. 

article
  • Used before one and words with initial u, eu. 

  • Used before a vowel sound. 

  • Used before all consonants. 

  • Used before /h/ in an unstressed syllable. 

  • Used before /h/ in a stressed syllable. 

num
  • one 

noun
  • The first letter of the Georgian alphabet, ა (Mkhedruli), Ⴀ (Asomtavruli) or ⴀ (Nuskhuri). 

to

prep
  • according to 

  • Used to indicate the target or recipient of an action. 

  • Used to indicate result of action. 

  • Used to indicate a ratio or comparison; compared to, as against. 

  • Used to indicate that the preceding term is to be raised to the power of the following value; indicates exponentiation. 

  • At. 

  • Used after an adjective to indicate its application. 

  • Preceding the next hour. 

  • Indicating destination: In the direction of, so as to arrive at. 

  • Denotes the end of a range. 

  • Often used without the hour 

  • Used to describe what something consists of or contains. 

  • Used to indicate a resulting feeling or emotion. 

adv
  • Toward a closed, touching or engaging position. 

  • Into the wind. 

particle
  • Used to indicate an obligation on the part of, or a directive given to, the subject. 

  • In order to. 

  • As above, with the verb implied. 

  • A particle used for marking the following verb as an infinitive. 

How often have the words an and to occurred in a corpus of books? (source: Google Ngram Viewer )