cp's OEIS Frontend

A121821 Decimal expansion of the Lucas binary number, Sum_{k>0} 1/2^L(k), where L(k) = A000032(k).

%I A121821 #4 Nov 07 2014 00:32:25
%S A121821 6,9,5,8,0,4,5,9,7,8,0,9,9,1,7,8,7,9,6,5,8,3,2,7,8,6,7,1,4,1,6,5,9,5,
%T A121821 5,9,7,7,9,5,1,3,2,7,1,8,5,4,8,5,6,1,2,0,0,4,3,1,5,7,2,2,0,5,7,4,6,0,
%U A121821 9,6,4,0,5,1,6,3,3,4,6,7,3,3,5,4,5,7,7,7,5,7,7,4,5,5,4,8,3,7,1,5,9,4,6,1,5
%N A121821 Decimal expansion of the Lucas binary number, Sum_{k>0} 1/2^L(k), where L(k) = A000032(k).
%C A121821 Its binary expansion is equal to 1 if n is Lucas number else 0.
%e A121821 0.6958045978099178796583278671416595597...
%t A121821 RealDigits[N[Sum[1/2^(Fibonacci[k-1]+Fibonacci[k+1]), {k, 1, 20}],150]]
%o A121821 (PARI) suminf(n=1,1/2^(fibonacci(n-1)+fibonacci(n+1))) \\ _Charles R Greathouse IV_, Nov 07 2014
%Y A121821 Cf. A000032, A000045, A084119, A010056.
%K A121821 cons,nonn
%O A121821 0,1
%A A121821 _Alexander Adamchuk_, Aug 26 2006