What does the backslash in Pari mean? As in: a(n) = 1 + n\4
It it very hard to find an answer using traditional search engines, because the terms "pari" and "backslash" appear in various independent contexts.
Instead of "traditional search engines", use Pari's online help: ?? \
The expression x \y is the Euclidean quotient of x and y. If y is a real
scalar, this is defined as floor(x/y) if y > 0, and ceil(x/y) if y < 0 and the
division is not exact. Hence the remainder x - (x\y)*y is in [0, |y|[.
Note that when y is an integer and x a polynomial, y is first promoted to a
polynomial of degree 0. When x is a vector or matrix, the operator is applied
componentwise.