Square Matrices Generated by Sequences of Riordan Arrays
Ângela Mestre and José Agapito
Centro de Análise Funcional, Estruturas Lineares e Aplicações
Grupo de Estruturas Algébricas, Lineares e Combinatórias
Departamento de Matemática
Faculdade de Cîencias, Universidade de Lisboa
1749-016 Lisboa
Portugal
Abstract:
We consider sequences of images of Riordan arrays under some Riordan
group automorphisms introduced by Bacher. We enclose their properties
into several infinite square arrays which turn out to be of combinatorial
interest. To illustrate our approach we consider Cameron and Nkwanta's
sequence of generalized RNA arrays (whose first term is the well-known
Nkwanta RNA array). Although this sequence of generalized RNA arrays was
originally established as a sequence of pseudo-involutions, we show that
it does not contain pseudo-involutions other than Nkwanta's array. We
also show that these arrays are actually images of a new array under
some of Bacher’s automorphisms. We study the combinatorics of some
square matrices related to the generalized RNA arrays and to sequences
of genuine pseudo-involutions generated by Nkwanta's array.
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(Concerned with sequences
A000027
A000079
A000124
A000125
A000127
A000217
A000292
A000384
A000389
A000580
A000582
A001288
A001519
A002492
A002662
A002664
A005408
A005843
A006261
A008859
A008860
A010966
A010968
A014105
A025581
A035039
A035041
A053126
A053127
A053128
A053129
A059993
A060163
A088305
A114284
A116722
A130883
A145018
A152948
A152950
A165747
A167499
A177787
A201347
A220074.)
Received April 2 2019; revised versions received November 4 2019; December 24 2019.
Published in Journal of Integer Sequences,
December 26 2019.
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