Fibonacci

Please help as I am going round in circles
trying to figure this out.

First of all the list reproduced below
via somebody's software is what I am trying to
duplicate in Excel ..

The first column is an input date
the second column shows the Fib et al sequence #
the third column shows the date which the
second column references .. eg .. using
1 March 2001 as input day 16 should be
23 March 2001 and so on.

There is a complication in that the number sequence
may be in trading days which I believe need to be
converted into calendar days .. I have been given
the formula TD*7/5 = CD .. anyway I have
tried to duplicate in Excel and I am just not
getting for each date shown below at the
sequence number the date 23March2001 .. the
1March2001 date is the only date at plus 16 which gives
me 23March2001.

3/ 1/2001 -- 16th day since is 23 March 2001
1/31/2001 -- 36th day since is 23 March 2001
1/ 3/2001 -- 55th day since is 23 March 2001
11/13/2000 -- 89th day since is 23 March 2001
9/28/2000 -- 121st day since is 23 March 2001
1/31/2000 -- 289th day since is 23 March 2001
10/18/1999 -- 361st day since is 23 March 2001
7/20/1998 -- 676th day since is 23 March 2001
11/26/1996 -- 1089th day since is 23 March 2001
10/24/1988 -- 3136th day since is 23 March 2001
7/ 2/1986 -- 3721st day since is 23 March 2001

Would really appreciate some help here.

Thanks .. De Dingus