How to generate an inline constexpr plain array of array in c++17

The question

I am writing a software in c++17 for which performances are absolutely critical. I would like available in a few key functions constants in arrays themselves in arrays. It matters that both these array are accessible by a integer value in such (or similar) manner :

int main()
{
    for (int i = 0; i < size_of_A ; i++)
    {
        for (int j = 0; j < size_of_B_in_A(i); j++)
        {
            std::cout << A[i][j];
        }
    }
}

This would be the kind of array we would like to create assuming some function int f(a, b)

A
{
    // B1
    {
        f(1, 1),
        f(1, 2),
        f(1, 3),
           ...
        f(1, large number)
    },
    // B2
    {
        f(2, 1),
           ...
        f(2, some other large number)
    },
    ... etc
}

The Twist

Each inner array may be of different size which we have will stored elsewhere, we have to find the size at compile time. I would rather not use std::vector for they are assumed slightly slower . Also an I suppose a std::vector would be stored on the heap which would be a performance issue in my specific case. Furthermore, std::vector cannot be used as "inline constexpr" which would be necessary as I expect to have a large amount of value in those array never going to change. I am fine with recompiling all those values each time but not keeping them in an external file by policy as I am to follow a strict coding style.

What I Have Tried

brace initializer

// A.hh

#pragma once

#include <iostream>

void test1();
void test2();

inline constexpr int B1[1] = {1};
inline constexpr int B2[2] = {2, 3};
inline constexpr int B3[3] = {4, 5, 6};

inline constexpr const int *A[3] = {B1, B2, B3};

// main.cc

#include "A.hh"

int main()
{
    std::cout << "values : ";
    for (int i = 0; i < 3; i++)
    {
        for (int j = 0; j <= i; j++)
        {
            std::cout << A[i][j];
        }
    }

    std::cout << "\n\naddress test : \n";
    std::cout << &A << '\n';
    test1();
    test2();
}

// somewhere.cc

#include "A.hh"

void test1()
{
    std::cout << &A << '\n';
}

// elsewhere.cc

#include "A.hh"

void test2()
{
    std::cout << &A << '\n';
}

which prints :

./a.out
values : 123456

address test :
0x56180505cd70
0x56180505cd70
0x56180505cd70

Therefore A has not been copied in main.cc, somewhere.cc and elsewhere.cc which is good. I would like to go further and be able to create a huge amount of values.

struct with constexpr

using tips found here , I do this to be able to perform operations during array construction.

// B.hh

#pragma once

#include <iostream>

template <int N>
struct X
{
    int arr[N];
    constexpr X(): arr()
    {
        for (int i = 0; i < N; i++)
        {
            arr[i] = i % 3;
        }
    }
};

inline constexpr auto A = X<500>();

// main.cc

#include "B.hh"

int main()
{
    for (int i = 0; i < 500; i++)
    {
        std::cout << A.arr[i];
    }
}

Which unsuspectingly prints out

012012 (etc)...

Finally an array of array

And this where I am stuck

#pragma once

#include <iostream>

template <int N>
struct sub_array
{
    int arr[N];
    constexpr sub_array() : arr()
    {
        for (int i = 0; i < N; i++)
        {
            arr[i] = i;
        }
    }
};

struct array
{
    sub_array</*what here ?*/> arr[100];

    constexpr array() : arr()
    {
        for (int i = 0; i < 100; i++)
        {
            int size = i * 2; // a very large number

            // the value of 'size' is not usable in a constant expression
            //
            // I see why it is, but I can't think of any other way
            arr[i] = sub_array<size>;
        }
    }
};

inline constexpr array A = array();

How can I build such kind of array ?

Thank you for your time and consideration.