Taxicab numbers: Difference between revisions

</pre>

=={{header|ZX Spectrum Basic}}==

This will, in the strictest sense, work. Don't hold your breath though; after six hours on an emulator at full speed it had generated the first 10 numbers. Getting to 2006 may take a while longer.

<lang zxbasic>10 DIM f(1626)

20 FOR x=1 TO 1626

30 LET f(x)=x*x*x: REM the ZX Spectrum's exponentiation function is legendarily slow

40 NEXT x

50 LET c=0

60 FOR x=1 TO 4294967295: REM the highest number the ZX Spectrum Basic can accurately hold internally; cuberoot max=1626, hence the table limit

70 LET k=0

80 FOR m=1 TO 1626

90 FOR n=m+1 TO 1626

100 IF f(m)+f(n)=x THEN GOTO 160

110 IF f(n)>=x THEN LET n=1626: REM overshot, break out of the loop

120 IF f(m)>=x THEN LET m=1626

130 NEXT n

140 NEXT m

150 NEXT x

160 IF k=1 THEN LET q=m: LET r=n: GO TO 230: REM got one!

170 LET o=m

180 LET p=n

190 LET k=1

200 NEXT n

210 NEXT m

220 NEXT x

220 LET c=c+1

230 IF c>25 AND c<2000 THEN GO TO 320

240 LET t$="": REM convert number to string; while ZX Spectrum Basic can store all the digits of integers up to 2^32-1, it will resort to scientific notation trying to display any more than eight digits

250 LET t=INT (x/100000)

260 LET b=x-t/100000

270 IF t=0 THEN GO TO 290: REM omit leading zero

280 LET t$=STR$ t

290 LET t$=t$+STR$ b

300 PRINT c;":";t$;"=";q;"^3+";r;"=";o;"^3+";r;"^3"

310 POKE 23692,10: REM suppress "scroll?" prompt when screen fills up at c=22

320 IF c=2006 THEN LET x=4294967295: LET n=1626: LET m=1626

330 NEXT n

340 NEXT m

350 NEXT x</lang>

{{out}}

<pre>1:1729=9^3+10^3=1^3+12^3

2:4104=9^3+15^3=2^3+16^3

3:13832=18^3+20^3=2^3+24^3

4:20683=19^3+24^3=10^3+27^3

5:32832=18^3+30^3=4^3+32^3

6:39312=15^3+33^3=2^3+34^3

7:40033=16^3+33^3=9^3+34^3

8:46683=27^3+30^3=3^3+36^3

9:64232=26^3+36^3=17^3+39^3

10:65728=31^3+33^3=12^3+40^3

D BREAK into program, 100:1