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A068702 Numbers n such that concatenation n^2, n and 1 is a prime. 4


%S 2,5,8,9,17,27,32,39,41,56,60,65,66,68,72,78,89,98,108,117,120,128,

%T 132,159,168,173,176,191,192,194,197,209,212,213,246,248,254,264,272,

%U 282,288,293,296,302,311,315,324,327,332,341,350,353,360,371,392,425,444

%N Numbers n such that concatenation n^2, n and 1 is a prime.

%H Vincenzo Librandi, <a href="/A068702/b068702.txt">Table of n, a(n) for n = 1..1000</a>

%e 8 is a member, as the concatenation of 8^2, 8 and 1 i.e. 6481 is a prime.

%e 32 is a member as 1024321 (concatenation of 32^2, 32 and 1) is prime.

%t Select[ Range[457], PrimeQ[ FromDigits[ Join[ IntegerDigits[ #^2], IntegerDigits[ # ], IntegerDigits[ #^0]]]] &]

%Y Cf. A088619, A068701.

%K base,nonn

%O 1,1

%A _Amarnath Murthy_, Mar 04 2002

%E More terms from _Jason Earls_, Jun 10 2002

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Last modified November 28 10:32 EST 2022. Contains 358411 sequences. (Running on oeis4.)