A153829 Index sequence to A089840: positions of bijections that preserve A153835, or equivalently, A127302 (the non-oriented form of binary trees).

0, 1, 3, 7, 15, 21, 27, 46, 68, 73, 74, 83, 84, 87, 88, 92, 114, 149, 169, 183, 184, 189, 190, 199, 202, 203, 225, 251, 252, 254, 261, 262, 268, 269, 270, 271, 299, 400, 515, 537, 539, 573, 575, 591, 593, 638, 753, 871, 894, 895, 990, 995, 996, 1110, 1132

Offset: 0

Author

Antti Karttunen, Jan 07 2009

Keywords

• nonn

Comments

These elements form a subgroup in A089840 (A089839). Such elements consists of only such clauses where each vertex stays at the same distance from the root of the binary tree and in the image tree will still be sibling to its original sibling in the pre-image tree.

Because A127302 can be computed as a fold and most of the recursive derivations of A089840 (i.e. tables A122201-A122204, A122283-A122290, A130400-A130403) are also folds, this sequence gives also the indices to those derived tables where bijections preserving A127302 occur.

Links

• A. Karttunen, Table of n, a(n) for n = 0..3109
• A. Karttunen, C-program for computing the initial terms of this sequence

Crossrefs

Superset of A153830. Apart from 0, has no other elements common with A153826. Cf. also A153831, A153827, A153829, A153832, A153833.