4.19

#include <iostream>
#include <iomanip>
using namespace std;

void calc(long &b, int &i) {
    b = (i % 2 == 0 ? b + 3 : b * 2);
}

int main() {
    setlocale(LC_ALL, "Russian");
    int n, i;
    long b = 0;
    cout << "Введите значение n (n > 0): ";
    cin >> n;
    n --;
    cout << "  n    b(n)" << endl;
    cout << setw(3) << 1 << setw(6) << b << endl;
    for (i = 0; i < n; i++) {
        calc(b, i);
        cout << setw(3) << i + 2 << setw(6) << b << endl;
    }
    return 0;
}