Random-ish Integer permuter based on https://preshing.com/20121224/how-to-generate-a-sequence-of-unique-random-integers/

PrimeQuadraticResiduePermuter.cs

using System;

public readonly struct PrimeQuadraticResiduePermuter32(UInt32 seed)
{
	public UInt32 this[UInt32 x] => Permute(Permute(unchecked(x + seed)) ^ Xor);
    	
	private const UInt32 Xor = 0x5bf03635;
	
	private static UInt32 Permute(UInt32 x)
	{
		const UInt32 prime = 4_294_967_291; // The largest prime less than 2^32 that is congruent to 3 mod 4.
		if (x >= prime)
			return x;  // The 5 integers out of range are mapped to themselves.
		var square = (UInt64) x * x;
		var residue = (UInt32)(square % prime);
		return x <= prime / 2 ? residue : prime - residue;
	}
}

public readonly struct PrimeQuadraticResiduePermuter64(UInt64 seed)
{
	public UInt64 this[UInt64 x] => Permute(Permute(unchecked(x + seed)) ^ Xor);
    	
	private const UInt64 Xor = 0x5bf036355bf03635;
	
	private static UInt64 Permute(UInt64 x)
	{
		const UInt64 prime = 18_446_744_073_709_551_427; // The largest prime less than 2^64 that is congruent to 3 mod 4.
		if (x >= prime)
			return x;  // The 188 integers out of range are mapped to themselves.
		var square = (UInt128) x * x;
		var residue = (UInt64)(square % prime);
		return x <= prime / 2 ? residue : prime - residue;
	}
}