function TForm1.GetEastern(y: integer): TDateTime;
const
  eday : array[0..18] of Integer = (14,3,23,11,31,18,8,28,16,5,25,13,2,22,10,30,17,7,27);
var
  dix,m   : Integer;
  dt      : TDateTime;
begin
  dix:=eday[seYear1.Value mod 19];
  if dix<21 then m:=4 else m:=3;
  dt:=EncodeDate(y,m,dix);
  m:=DayofTheWeek(dt);
  if m=7 then dt:=IncDay(dt,1);
  Result:=DateOf(EndOfTheWeek(dt));
end;

procedure TForm1.GetFDays;
var
  dt     : TDateTime;
  i      : integer;
begin
  fdays[0]:=EncodeDate(seYear1.Value,1,1);     //Neujahr
  fdays[1]:=EncodeDate(seYear1.Value,1,6);     //Heil.dr.Könige
  dt:=GetEastern(seYear1.Value);
  fdays[2]:=IncDay(dt,-2);                     //Karfreitag
  fdays[3]:=IncDay(dt,1);                      //Ostermontag
  fdays[4]:=EncodeDate(seYear1.Value,5,1);     //1.Mai
  fdays[5]:=IncDay(dt,39);                     //Himmelfahrt
  fdays[6]:=IncDay(dt,50);                     //Pfingstmontag
  fdays[7]:=IncDay(fdays[6],10);               //Fronleichnam
  dt:=EncodeDate(seYear1.Value,12,24);
  i:=0;
  repeat
    dt:=IncDay(dt,-1);
    if DayOfTheWeek(dt)=7 then inc(i);
  until i=5;
  repeat dt:=IncDay(dt,-1) until DayOfTheWeek(dt)=3;
  fdays[8]:=EncodeDate(seYear1.Value,8,15);    //Maria Himmelfahrt
  fdays[9]:=EncodeDate(seYear1.Value,10,3);    //Tag d.d.Einheit
  fdays[10]:=EncodeDate(seYear1.Value,10,31);  //Reformationstag
  fdays[11]:=EncodeDate(seYear1.Value,11,1);   //Allerheiligen
  fdays[12]:=dt;                               //Buß-u.Bettag
  fdays[13]:=EncodeDate(seYear1.Value,12,25);  //1.Weihnachtstag
  fdays[14]:=EncodeDate(seYear1.Value,12,26);  //2.Weihnachtstag
end;