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A261545 a(n) indicates which letter of the English alphabet is the n-th most common. 0
5, 20, 1, 15, 9, 14, 19, 18, 8, 12, 4, 3, 21, 13, 6, 16, 7, 23, 25, 2, 22, 11, 24, 10, 17, 26 (list; graph; refs; listen; history; text; internal format)



This is according to Mayzner revisited (Peter Norvig), Cornell, British National Corpus and the Brown corpus.


Martin Gardner, "Codes, Ciphers, and Secret Writing." Dover Publications, Inc. New York 1984.

M. S. Mayzner, Margaret Elizabeth Tresselt, "Tables of Single-letter and Digram Frequency Counts for Various Word-length and Letter-position Combinations," Psychonomic Press, 1965.

A. Young," Mathematical Ciphers: From Caesar to RSA." Mathematical World, Volume 25. American Mathematical Society 2006.


Table of n, a(n) for n=1..26.

Cornell, Department of Mathematics, Math Explorer's Club, English Letter Frequency.

Gifted Mathematics,  Learn How to be Successful in Mathematics Competitions Worldwide, The Undecipherable Cipher: Middle Secondary Mathematics.

Brian Kelk, Some examples of letter frequency rankings in English.

Peter Norvig, English Letter Frequency Counts: Mayzner Revisited or ETAOIN SRHLDCU.

Prooffreader.com, Graphing the distribution of English letters towards the beginning, middle or end of words. [Via Wayback Machine]

Wikipedia, Letter frequency.

Wikipedia, Gadsby (novel).


The most common letter of the English alphabet is the fifth letter 'E', so a(1)=5; the second most common letter is the twentieth letter 'T', so a(2)=20; the third most common letter is 'A', so a(3)=1; etc.


ToCharacterCode["etaoinsrhldcumfpgwybvkxjqz"] - 96


Cf. A005224, A049525, A055508, A126810.

Sequence in context: A122152 A104314 A302662 * A093482 A283522 A199363

Adjacent sequences:  A261542 A261543 A261544 * A261546 A261547 A261548




Peter Norvig and Robert G. Wilson v, Aug 24 2015



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Last modified July 24 13:37 EDT 2021. Contains 346273 sequences. (Running on oeis4.)