Рунге–кутта 4-го порядка и метод эйлера должны совпадать в ответах?

//PascalABC.NET 3.1 сборка 1239
uses System;
uses System.Collections;

begin
    var d := DateTime.Today;
    repeat
        d := d.AddDays(1);
    until d.DayOfWeek = DayOfWeek.Sunday;
    
    var Sundays := new Dictionary<integer, integer>();
    
    repeat
        if Sundays.ContainsKey(d.Year) then
            Sundays[d.Year] += 1
        else
            Sundays.Add(d.Year, 1);
        
        d := d.AddDays((-7));
    until d.Year <= 1;
    
    var max := Sundays.Values.Max;
    Sundays.Where(x -> x.Value = max).Println;
end.

ответ 31

код на Ruby 22

for i in 1..40
    s = i.to_s(2)
    k = 0
    s.chars().each {|c| k += 1 if c == "1" }
    s += (k % 2).to_s + "0"
    p [i, s, s.to_i(2)]
end

вывод
[1, "110", 6]
[2, "1010", 10]
[3, "1100", 12]
[4, "10010", 18]
[5, "10100", 20]
[6, "11000", 24]
[7, "11110", 30]
[8, "100010", 34]
[9, "100100", 36]
[10, "101000", 40]
[11, "101110", 46]
[12, "110000", 48]
[13, "110110", 54]
[14, "111010", 58]
[15, "111100", 60]
[16, "1000010", 66]
[17, "1000100", 68]
[18, "1001000", 72]
[19, "1001110", 78]
[20, "1010000", 80]
[21, "1010110", 86]
[22, "1011010", 90]
[23, "1011100", 92]
[24, "1100000", 96]
[25, "1100110", 102]
[26, "1101010", 106]
[27, "1101100", 108]
[28, "1110010", 114]
[29, "1110100", 116]
[30, "1111000", 120]
[31, "1111110", 126]
[32, "10000010", 130]
[33, "10000100", 132]
[34, "10001000", 136]
[35, "10001110", 142]
[36, "10010000", 144]
[37, "10010110", 150]
[38, "10011010", 154]
[39, "10011100", 156]
[40, "10100000", 160]