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A244555
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Primes which remain prime when the last digit is replaced by its square.
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2
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11, 13, 17, 19, 23, 29, 31, 37, 41, 47, 53, 61, 71, 73, 83, 89, 101, 103, 107, 127, 131, 139, 149, 151, 157, 173, 181, 191, 193, 197, 211, 223, 229, 233, 239, 241, 251, 257, 263, 271, 277, 281, 307, 311, 331, 347, 353, 359, 373, 383, 389, 401, 421, 431, 433
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OFFSET
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1,1
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..9000
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EXAMPLE
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107 is in the sequence because 7^2=49 and 1049 is a prime.
449 is in the sequence because 9^2=81 and 4481 is a prime.
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MATHEMATICA
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selQ[p_] := (id = IntegerDigits[p]; id1 = Most[id]; id2 = Last[id]^2 // IntegerDigits; p2 = Join[id1, id2] // FromDigits; PrimeQ[p2]); Select[Array[Prime, 100], selQ] (* Jean-François Alcover, Jul 04 2014 *)
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PROG
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(Magma) r:=func<i | Seqint(Intseq(Intseq(i)[1]^2) cat Intseq(Floor(i/10)))>; [p: p in PrimesUpTo(500) | IsPrime(r(p))]; // Bruno Berselli, Jul 04 2014
(PARI) lista(nn) = {forprime(p=2, nn, d = p % 10; if (isprime(eval(concat(Str(p\10), Str(d^2)))), print1(p, ", ")); ); } \\ Michel Marcus, Jul 04 2014
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CROSSREFS
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Cf. A030430 (subsequence).
Sequence in context: A135779 A135778 A078875 * A052293 A038842 A293660
Adjacent sequences: A244552 A244553 A244554 * A244556 A244557 A244558
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KEYWORD
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nonn,base
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AUTHOR
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Vincenzo Librandi, Jul 02 2014
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STATUS
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approved
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