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+--- Thread: (49G) A Fibonacci-like Sequence with Only Composite Members (/thread-4331.html)
(49G) A Fibonacci-like Sequence with Only Composite Members - Gerald H - 07-09-2015 05:10 PM
A programme to produce a Fibonacci-like sequence but starting with zeroth element
106276436867
& first element
35256392432
the following numbers being the sum of the preceding two elements of the series.
Interestingly, every element of the series is a composite number.
Input an integer N to find the Nth sequence element.
Code:
::
CK1&Dispatch
BINT1
::
%ABSCOERCE
ZINT 106276436867
SWAP
DUP#0=csDROP
ZINT 35256392432
SWAPDUP
#1=case
DROPSWAPDROP
FPTR2 ^#>Z
::
DUP
Z2_
Z<
case
::
BINT4
NDUPN
DROP
;
FPTR2 ^Z>ZH
Z-2_
Z0Z1_
4PICK
FPTR2 ^ZBits
SWAPDROP#1-_
ZERO_DO
FPTR2 ^ZSQ_
SWAP
FPTR2 ^ZSQ_
2DUP
FPTR2 ^RSUBext
DUP
FPTR2 ^RADDext
3PICK
FPTR2 ^RADDext
3UNROLL
FPTR2 ^RADDext
SWAPROT
FPTR2 ^RADDext
3PICK
ISTOP-INDEX
#1-
FPTR2 ^ZBit?
SWAPDROP
ITE
::
DUPUNROT
FPTR2 ^QAdd
Z-2_
;
Z2_
3UNROLL
LOOP
;
2SWAP
2DROP
ROT
FPTR2 ^RMULText
3UNROLL
FPTR2 ^RMULText
FPTR2 ^RADDext
;
;