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A068492
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Primes which remain prime after each digit is replaced by its square.
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1
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11, 13, 17, 19, 71, 73, 89, 101, 103, 107, 131, 137, 149, 167, 173, 191, 197, 199, 223, 229, 233, 283, 307, 311, 313, 331, 337, 359, 383, 401, 433, 439, 461, 463, 491, 523, 569, 593, 631, 641, 647, 659, 709, 733, 743, 773, 809, 823, 859, 907, 911, 919, 947
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Zak Seidov, Table of n, a(n) for n = 1..1000
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EXAMPLE
| When each digit of the prime 89 is replaced by its square, 6481, a prime, results. Hence 89 is a term of the sequence.
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MATHEMATICA
| f[n_] := Block[{a = IntegerDigits[n], b = "", k = 1, l}, l = Length[a]; While[k < l + 1, b = StringJoin[b, ToString[a[[k]]^2]]; k++ ]; ToExpression[b]]; Do[ If[ PrimeQ[ f[ Prime[n]]], Print[ Prime[n]]], {n, 1, 150} ]
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PROG
| (MAGMA) DigitsSquared:=func< n | StringToInteger(&cat[ IntegerToString(a): a in Reverse([ d^2: d in Intseq(n) ]) ]) >; IsA068492:=func< p | IsPrime(DigitsSquared(p)) >; [ p: p in PrimesUpTo(1000) | IsA068492(p) ]; // Klaus Brockhaus, Mar 05 2011
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CROSSREFS
| Sequence in context: A157175 A132244 A087201 * A206287 A045707 A032591
Adjacent sequences: A068489 A068490 A068491 * A068493 A068494 A068495
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KEYWORD
| base,nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Mar 11 2002
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EXTENSIONS
| Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com) Mar 19 2002
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