A261510 - OEIS

%I #20 Aug 25 2016 21:42:09

%S 1111211111,1111411111,3333133333,9999499999,

%T 1111111111112111111111111111,1111311331137311333311111111,

%U 1111411441142411444411111111,1111611661167611666611111111,1111811881185811888811111111,3333033003305033000033333333,3333133113312133111133333333

%N Triangle-congruent primes greater than 10 with a single digit at the center.

%C Subsequence of A050758.

%H G. L. Honaker, Jr. and C. Caldwell, <a href="https://primes.utm.edu/curios/page.php?number_id=7464">1111211111</a>

%e a(6) can be represented as follows:

%e ......1

%e .....1 1

%e ....1 3 1

%e ...1 3 3 1

%e ..1 3 7 3 1

%e .1 3 3 3 3 1

%e 1 1 1 1 1 1 1

%Y Cf. A050758.

%K nonn,base

%O 1,1

%A _Felix Fröhlich_, Aug 22 2015