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Truncatable primes: Difference between revisions
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Putting Maple in alphabetical order
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print( "max_prime_right = ", max_prime_right )</lang>
=={{header|Mathematica}}==▼
<lang Mathematica>LeftTruncatablePrimeQ[n_] := Times @@ IntegerDigits[n] > 0 &&▼
And @@ PrimeQ /@ ToExpression /@ StringJoin /@ ▼
Rest[Most[NestList[Rest, #, Length[#]] &[Characters[ToString[n]]]]]▼
RightTruncatablePrimeQ[n_] := Times @@ IntegerDigits[n] > 0 &&▼
And @@ PrimeQ /@ ToExpression /@ StringJoin /@ ▼
Rest[Most[NestList[Most, #, Length[#]] &[Characters[ToString[n]]]]]</lang>▼
Example usage:▼
<pre>n = PrimePi[1000000]; While[Not[LeftTruncatablePrimeQ[Prime[n]]], n--]; Prime[n]▼
-> 998443▼
n = PrimePi[1000000]; While[Not[RightTruncatablePrimeQ[Prime[n]]], n--]; Prime[n]▼
-> 739399</pre>▼
=={{header|Maple}}==
Line 1,706 ⟶ 1,693:
998443
</pre>
▲=={{header|Mathematica}}==
▲<lang Mathematica>LeftTruncatablePrimeQ[n_] := Times @@ IntegerDigits[n] > 0 &&
▲ And @@ PrimeQ /@ ToExpression /@ StringJoin /@
▲ Rest[Most[NestList[Rest, #, Length[#]] &[Characters[ToString[n]]]]]
▲RightTruncatablePrimeQ[n_] := Times @@ IntegerDigits[n] > 0 &&
▲ And @@ PrimeQ /@ ToExpression /@ StringJoin /@
▲ Rest[Most[NestList[Most, #, Length[#]] &[Characters[ToString[n]]]]]</lang>
▲Example usage:
▲<pre>n = PrimePi[1000000]; While[Not[LeftTruncatablePrimeQ[Prime[n]]], n--]; Prime[n]
▲-> 998443
▲n = PrimePi[1000000]; While[Not[RightTruncatablePrimeQ[Prime[n]]], n--]; Prime[n]
▲-> 739399</pre>
=={{header|MATLAB}}==
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