OFFSET
0,3
COMMENTS
This automorphism is illustrated below, where letters A, B and C refer to arbitrary subtrees located on those nodes and () stands for an implied terminal node.
............................B...C.......C...D..............................
.............................\./.........\./...............................
.A...B.............B...C......x...D....B..x............()...C......C..()...
..\./...............\./........\./......\./.............\./.........\./....
...x...C..-->....A...x......()..x...-->..x..().......()..x....-->....x..().
....\./...........\./........\./..........\./.........\./.............\./..
.....x.............x..........x............x...........x...............x...
See the comments at A123695.
LINKS
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 11 2006
STATUS
approved