A079440 Number of transpositions (2-cycles) in range [A014137(n-1)..A014138(n-1)] of permutation A057505 (= Donaghey's automorphism M).

0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 6, 6, 6, 7, 8, 8, 9, 9, 11, 12, 12, 12, 14, 14, 14, 15, 17, 17, 18, 18, 19, 20, 20, 20, 23, 23, 23, 24, 25, 25, 26, 26, 28, 29, 29, 29, 31, 31, 31, 32, 34, 34, 35, 35, 36, 37, 37, 37, 40, 40, 40, 41, 42, 42, 43, 43, 45, 46, 46, 46, 48, 48, 48

Offset: 0

Author

Antti Karttunen, Jan 27 2003

Keywords

• nonn

Links

• Robert Donaghey, Automorphisms on Catalan trees and bracketing, J. Combin. Theory, Series B, 29 (1980), 75-90.
• Antti Karttunen, Illustration of initial terms for trees of sizes n=2..18

Crossrefs

From n>= 2 onward a(n) = A079438(n)/2 (with the same reservation). Cf. A079444.

Programs

Maple

A079440 := n -> floor((n+1)/3) + `if`((n>=14),floor((n-10)/4)+floor((n-14)/8),0);