%I A125725
%S A125725 0,2,16,114,800,5602,39216,274514,1921600,13451202,94158416,659108914,
%T A125725 4613762400,32296336802,226074357616,1582520503314,11077643523200,
%U A125725 77543504662402,542804532636816,3799631728457714,26597422099204000
%N A125725 Numbers whose base 7 representation is 222....2.
%F A125725 a(n)=2*(7^n-1)/6.
%F A125725 a(n)=7*a(n-1)+2 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), 
               Oct 30 2009]
%e A125725 base 7.......decimal
%e A125725 0..................0
%e A125725 2..................2
%e A125725 22................16
%e A125725 222..............114
%e A125725 2222.............800
%e A125725 22222...........5602
%e A125725 222222.........39216
%e A125725 2222222.......274514
%e A125725 22222222.....1921600
%e A125725 222222222...13451202
%e A125725 etc...........etc.
%e A125725 For n=2, a(2)=7*0+2=2; n=3, a(3)=7*2+2=16; n=4, a(4)=7*16+2=114 [From 
               Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 30 2009]
%p A125725 seq(2*(7^n-1)/6, n=0..20);
%Y A125725 Sequence in context: A117627 A117628 A037564 this_sequence A162723 A159324 
               A088755
%Y A125725 Adjacent sequences: A125722 A125723 A125724 this_sequence A125726 A125727 
               A125728
%K A125725 easy,nonn
%O A125725 0,2
%A A125725 Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 02 2007