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 A068702 Numbers n such that concatenation n^2, n and 1 is a prime. 4
 2, 5, 8, 9, 17, 27, 32, 39, 41, 56, 60, 65, 66, 68, 72, 78, 89, 98, 108, 117, 120, 128, 132, 159, 168, 173, 176, 191, 192, 194, 197, 209, 212, 213, 246, 248, 254, 264, 272, 282, 288, 293, 296, 302, 311, 315, 324, 327, 332, 341, 350, 353, 360, 371, 392, 425, 444 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 EXAMPLE 8 is a member, as the concatenation of 8^2, 8 and 1 i.e. 6481 is a prime. 32 is a member as 1024321 (concatenation of 32^2, 32 and 1) is prime. MATHEMATICA Select[ Range[457], PrimeQ[ FromDigits[ Join[ IntegerDigits[ #^2], IntegerDigits[ # ], IntegerDigits[ #^0]]]] &] CROSSREFS Cf. A088619, A068701. Sequence in context: A173286 A243182 A088620 * A083724 A072476 A167541 Adjacent sequences: A068699 A068700 A068701 * A068703 A068704 A068705 KEYWORD base,nonn AUTHOR Amarnath Murthy, Mar 04 2002 EXTENSIONS More terms from Jason Earls, Jun 10 2002 STATUS approved

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Last modified July 13 06:34 EDT 2024. Contains 374267 sequences. (Running on oeis4.)