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%I #7 Jul 16 2021 21:34:41
%S 1,2,6,3022
%N Numbers k such that (k concatenated k times) + 1 = A000461(k) + 1 is a prime number.
%C The (probable) prime corresponding to a(4)=3022, i.e., 3022302230...3023 has 12088 digits. Next term is greater than 5000.
%H <a href="http://groups.yahoo.com/group/primeform/">Primeform:</a> User group for PFGW and PrimeForm programs. [There is insufficient information to determine which posting to the forum was intended. Probably not worth pursuing. - _N. J. A. Sloane_, Nov 10 2019]
%e 1, 2 and 6 are terms since 1+1, 22+1 and 666666+1 are prime numbers.
%Y Cf. A000461.
%K base,hard,more,nonn
%O 1,2
%A _Giovanni Resta_, Mar 07 2006
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