2011/07/27 by Barry, Paul
#11B83 #11C20 #15B05 #Combinatorics (math.CO) #FOS: Mathematics #Primary 15B36 #Secondary 11B37
paper · doi:10.48550/arxiv.1107.5490
Using the language of Riordan arrays, we look at two related iterative processes on matrices and determine which matrices are invariant under these processes. In a special case, the invariant sequences that arise are conjectured to have Hankel transforms that obey Somos-4 recurrences. A notion of eigentriangle for a number triangle emerges and examples are given, including a construction of the Takeuchi numbers.