4 problems

Row sum polynomial conjecture. For every $n\geq 0$,

Robbins-number amalgamation conjecture. The principal minor sequence of this amalgamation is the sequence of Robbins numbers.

Let $M=(g(x),f(x))$ be a Riordan array, and let $P^{(n)}_M$ denote its $n$-th production matrix, defined by … Let $M^{(n)}$ be the matrix produced by $P^{(n)}_M$. Higher production…

Somos 4 conjecture. The Hankel transform of the expansion of $f(x)/x$ is a