A285727 a(1) = a(2) = 0, and for n > 2, a(n) = A252463(A252463(n)).

0, 0, 1, 1, 2, 2, 3, 2, 2, 3, 5, 3, 7, 5, 3, 4, 11, 4, 13, 5, 5, 7, 17, 6, 4, 11, 4, 7, 19, 6, 23, 8, 7, 13, 6, 9, 29, 17, 11, 10, 31, 10, 37, 11, 6, 19, 41, 12, 9, 9, 13, 13, 43, 8, 10, 14, 17, 23, 47, 15, 53, 29, 10, 16, 14, 14, 59, 17, 19, 15, 61, 18, 67, 31, 9, 19, 15, 22, 71, 20, 8, 37, 73, 21, 22, 41, 23, 22, 79, 12, 21, 23, 29, 43, 26, 24, 83, 25, 14

Offset: 1

Author

Antti Karttunen, Apr 25 2017

Keywords

• nonn

Comments

For n >= 3, a(n) gives the contents of the grandparent node of the node containing n in binary trees like A005940 and A163511.

Each number larger than one occurs exactly four times in this sequence.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..8192

Crossrefs

Cf. A005940, A064989, A163511, A252463, A285728.

Programs

Scheme

(define (A285727 n) (if (<= n 2) 0 (A252463 (A252463 n))))

Formula

a(1) = a(2) = 0, and for n > 2, a(n) = A252463(A252463(n)).

For n > 2, if n is even, a(n) = A252463(n/2), otherwise a(n) = A252463(A064989(n)).