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%I #8 Jun 09 2023 22:59:11
%S 3,11,21,29,39,47,59,69,101,111,131,149,171,183,197,213,231,243,249,
%T 251,297,299,317,323,329,369,387,401,411,423,431,461,501,521,527,533,
%U 537,539,543,593,651,657,669,717,741,743,779,819,867,869,873,897,939,981
%N Numbers k such that the concatenation of 1, k and k^2 is prime.
%e 3 is a member as 139 is a prime. 11 is a member as 111121 (concatenation of 1,11 and 121) is prime.
%t Select[ Range[1000], PrimeQ[ FromDigits[ Join[ IntegerDigits[ #^0], IntegerDigits[ # ], IntegerDigits[ #^2]]]] &]
%Y Cf. A068702.
%K base,nonn
%O 1,1
%A _Amarnath Murthy_, Oct 17 2003
%E Edited and extended by _Robert G. Wilson v_ and _Ray Chandler_, Oct 18 2003
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