%I #3 Mar 11 2014 01:34:10

%S 1,12,123,1234,12345,123457,1234578,12345789,1234578910,123457891011,

%T 12345789101112,1234578910111213,123457891011121314,

%U 12345789101112131415,1234578910111213141516,123457891011121314151617

%N Concatenation of first n imperfect numbers.

%H Omar E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica de los numeros primos y perfectos</a>.

%Y Imperfect numbers: A132999. Cf. A000396, A007908, A019518, A132928.

%K easy,nonn,base

%O 1,2

%A _Omar E. Pol_, Oct 16 2007