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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 August 6 16:05 EDT 2020. Contains 336255 sequences. (Running on oeis4.)