%I #3 Mar 30 2012 18:50:57
%S 1,13,341,19531,2015539,329554457,78536544841,25736391511831,
%T 11111111111111111,6115909044841454629,4182283628124518315101,
%U 3479492117784426363920483,3461445831219105624193478971
%N Values of repunits with odd length L in base (L+3)/2 representation.
%C Central terms of the triangle in A125118: a(n)=A125118(2*n-1,n).
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Repunit.html">Repunit</a>
%F a(n) = Sum((n+1)^k: 0<=k<=2*(n-1)).
%e a(4) = [1111111]_5 = (((((5+1)*5+1)*5+1)*5+1)*5+1)*5+1 = 19531.
%K nonn,base
%O 1,2
%A _Reinhard Zumkeller_, Nov 21 2006