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%I #12 Sep 08 2022 08:45:14
%S 0,15,1155,111555,11115555,1111155555,111111555555,11111115555555,
%T 1111111155555555,111111111555555555,11111111115555555555,
%U 1111111111155555555555,111111111111555555555555
%N a(n) = -1 + A093137(n)^2.
%H Vincenzo Librandi, <a href="/A098210/b098210.txt">Table of n, a(n) for n = 0..100</a>
%F a(n) = (1/9)*(10^n-1)*(5+10^n). - _Vincenzo Librandi_, Jun 02 2013
%e Like other -1 + square of near-repdigits give special digit patterns: (33333334^2) - 1 = 11111115555555.
%t Table[(1/9) (10^n - 1) (5 + 10^n), {n, 0, 25}] (* _Vincenzo Librandi_, Jun 02 2013 *)
%o (Magma) [(1/9)*(10^n-1)*(5+10^n): n in [0..15]]; // _Vincenzo Librandi_, Jun 02 2013
%Y Cf. A093137.
%K nonn,easy
%O 0,2
%A _Labos Elemer_, Oct 20 2004