Find adjacent primes which differ by a square integer: Difference between revisions
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</pre> |
</pre> |
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=={{header|GW-BASIC}}== |
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<lang gwbasic>10 P=3 : P2=0 |
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20 GOSUB 180 |
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30 IF P2>1000000! THEN END |
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40 R = P2-P |
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50 IF R > 36 AND INT(SQR(R))^2=R THEN PRINT P,P2,R |
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60 P=P2 |
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70 GOTO 20 |
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80 REM tests if a number is prime |
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90 Q=0 |
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100 IF P = 2 THEN Q = 1:RETURN |
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110 IF P=3 THEN Q=1:RETURN |
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120 I=1 |
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130 I=I+1 |
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140 IF INT(P/I)*I = P THEN RETURN |
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150 IF I*I<=P THEN GOTO 130 |
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160 Q = 1 |
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170 RETURN |
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180 REM finds the next prime after P, result in P2 |
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190 IF P = 0 THEN P2 = 2: RETURN |
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200 IF P<3 THEN P2 = P + 1: RETURN |
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210 T = P |
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220 P = P + 1 |
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230 GOSUB 80 |
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240 IF Q = 1 THEN P2 = P: P = T: RETURN |
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250 GOTO 220</lang> |
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=={{header|PARI/GP}}== |
=={{header|PARI/GP}}== |