100 PROGRAM "Fibonac.bas"
110 FOR I=0 TO 20
120 PRINT "F";I,FIB(I)
130 NEXT
140 DEF FIB(N)
150 NUMERIC I
160 LET A=0:LET B=1
170 FOR I=1 TO N
180 LET T=A+B:LET A=B:LET B=T
190 NEXT
200 LET FIB=A
210 END DEF