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José María Grau Ribas
  • Member for 1 year, 9 months
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11 votes
3 answers
1k views

What is the limit of $a (n + 1) / a (n)$?

6 votes
1 answer
465 views

Do you know which is the minimal local ring that is not isomorphic to its opposite?

4 votes
0 answers
159 views

Do you know rings without involutions, auto-anti-isomorphics? In that case, what is the minimal example?

3 votes
1 answer
228 views

Number of rings with additive group $(\mathbb{Z}_{16})^2$. A341547(16) in OEIS

3 votes
1 answer
243 views

A generating function related to the Delannoy numbers

3 votes
1 answer
138 views

About the sequence $s_n:=f_{n,n} $ where $f_{0,n}=f_{n,0}= n^n$ and $f_{m,n} = f_{m-1,n}+ f_{m,n-1} + f_{m-1,n-1}$

2 votes
0 answers
107 views

Existence and uniqueness of solution of a nonlinear system

1 vote
2 answers
243 views

How many non-isomorphic associative algebras of dimension 2 over the field F_{p^k} are there?

1 vote
0 answers
187 views

Why $\lim_{n\rightarrow \infty}\frac{F(n,n)}{F(n-1,n)} =\lim_{n\rightarrow \infty}\frac{F(n+1,n)}{F(n,n)} $?

1 vote
1 answer
296 views

Why $\lim_{n\rightarrow \infty}\frac{F(n,n)}{F(n-1,n-1)} =\frac{9}{8}$?

1 vote
1 answer
136 views

Do you know a finite unitary reversible ring that is not isomorphic to its opposite? And the minimal with that property?

0 votes
1 answer
233 views

Given a unitary commutative ring $R$, what are the rings $R\langle x,y\rangle/(x^2-A,y^2-B,yx-a-bx-cy-dxy)$ called

0 votes
1 answer
110 views

What is the computational complexity of the calculation of $ \Psi(x) $?

0 votes
1 answer
142 views

How to probe the recursiveness order of a sequence $\{S_n\}$ whose generating function is known

0 votes
0 answers
108 views

Is the sequence $s_n:=f_{n,n} $ where $f_{0,n}=f_{n,0}= n!$ and $f_{m,n} = f_{m-1,n}+ f_{m,n-1} + f_{m-1,n-1}$ P-recursive?