%I A106710
%S A106710 0,26,1326,50726,1725126
%N A106710 Number of words with n letters from an alphabet of size 26 with at least 
               two equal consecutive letters.
%F A106710 a(n) = 26^n - 26*(25^(n - 1))
%e A106710 a(3) = 1326 because 26^3 - 26*(25^2) = 1326
%Y A106710 Sequence in context: A037138 A091429 A160311 this_sequence A114052 A042303 
               A042300
%Y A106710 Adjacent sequences: A106707 A106708 A106709 this_sequence A106711 A106712 
               A106713
%K A106710 nonn
%O A106710 0,2
%A A106710 Luca Colucci (lcolucci(AT)caridata.it), May 14 2005