(11C) Tribonacci Sequence

[Dieter]

(12-14-2017 12:21 PM)Gamo Wrote:  The Tribonacci Sequence is a generalization of the Fibonacci sequence where each term is the sum of the three preceding terms.

The sequence begins 0, 1, 1, 2, 4, 7, 13, 24, 44, 81, 149,. . . .

Input the Nth number
Example: 7 A result 24
_______10 A result 149

Interesting formula. But implemented waaayyy too complicated. ;-)
Actually it's nothing more than u · vⁿ with u and v being two constants.

So what about this one:

Code:

LBL C
ENTER
1,839286755
STO 0
x<>y
y^x
RCL 0
4
x
RCL 0
x^2
-
1
-
/
,4
+
INT
RTN

Or simply...

Code:

LBL C
ENTER
1,839286755
x<>y
y^x
,336228117
x
,4
+
INT
RTN

Dieter