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A244556 Primes p that do not remain prime if their last digit is replaced by its square. 1
2, 3, 5, 7, 43, 59, 67, 79, 97, 109, 113, 137, 163, 167, 179, 199, 227, 269, 283, 293, 313, 317, 337, 349, 367, 379, 397, 409, 419, 439, 463, 479, 487, 499, 523, 557, 569, 607, 617, 619, 643, 673, 677, 683, 709, 719, 727, 739, 743, 773, 787 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

EXAMPLE

59 is in the sequence because 9^2 = 81 and 581 is not prime.

727 is in the sequence because 7^2 = 49 and 7249 is not prime.

MATHEMATICA

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] (* see Jean-François Alcover in A244555 *)

PROG

(Magma) r:=func<i | Seqint(Intseq(Intseq(i)[1]^2) cat Intseq(Floor(i/10)))>; [p: p in PrimesUpTo(800) | not IsPrime(r(p))]; // Bruno Berselli, Jul 04 2014

CROSSREFS

Cf. A244555.

Sequence in context: A286319 A090716 A083820 * A279954 A120804 A092066

Adjacent sequences: A244553 A244554 A244555 * A244557 A244558 A244559

KEYWORD

nonn,base

AUTHOR

Vincenzo Librandi, Jul 02 2014

STATUS

approved

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Last modified February 6 05:24 EST 2023. Contains 360097 sequences. (Running on oeis4.)