cp's OEIS Frontend

A170940 4^n-2^n-2.

%I A170940 #8 Jul 28 2015 16:39:50
%S A170940 0,10,54,238,990,4030,16254,65278,261630,1047550,4192254,16773118,
%T A170940 67100670,268419070,1073709054,4294901758,17179738110,68719214590,
%U A170940 274877382654,1099510579198,4398044413950,17592181850110,70368735789054,281474959933438,1125899873288190
%N A170940 4^n-2^n-2.
%C A170940 a(n) is also the number whose binary representation is the concatenation of n-1 1's, 0, n-1 1's and 0 (See example). [From _Omar E. Pol_, Mar 16 2010]
%H A170940 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (7, -14, 8).
%F A170940 a(n)= 7*a(n-1) -14*a(n-2) +8*a(n-3) = 2*A129868(n-1). G.f.: 2*x^2*(-5+8*x)/((x-1) * (2*x-1) * (4*x-1)). [From _R. J. Mathar_, Feb 14 2010]
%F A170940 a(n) = 2*(A006516(n)-1) [From _Omar E. Pol_, Mar 16 2010]
%e A170940 Contribution from _Omar E. Pol_, Mar 16 2010: (Start)
%e A170940 n ...... a(n) written in base 2 ..... a(n)
%e A170940 1 ................ 0 ................ 0
%e A170940 2 ............... 1010 .............. 10
%e A170940 3 .............. 110110 ............. 54
%e A170940 4 ............. 11101110 ............ 238
%e A170940 5 ............ 1111011110 ........... 990
%e A170940 6 ........... 111110111110 .......... 4030
%e A170940 7 .......... 11111101111110 ......... 16254
%e A170940 8 ......... 1111111011111110 ........ 65278
%e A170940 9 ........ 111111110111111110 ....... 261630
%e A170940 10 ...... 11111111101111111110 ...... 1047550
%e A170940 (End)
%Y A170940 Cf. A170926.
%Y A170940 Cf. A006516, A138148, A173521. [From _Omar E. Pol_, Mar 16 2010]
%K A170940 nonn
%O A170940 1,2
%A A170940 _N. J. A. Sloane_, Feb 13 2010