A269991 Decimal expansion of Sum_{n >= 1} 2^(1-n)/Fibonacci(n).

1, 6, 8, 4, 8, 1, 3, 1, 4, 4, 4, 8, 9, 5, 7, 6, 0, 9, 6, 3, 1, 6, 5, 5, 4, 3, 3, 7, 3, 8, 0, 0, 7, 8, 2, 3, 0, 2, 3, 7, 0, 6, 3, 8, 8, 2, 4, 5, 7, 0, 8, 6, 8, 2, 0, 9, 4, 3, 1, 7, 6, 1, 8, 8, 5, 9, 5, 0, 5, 6, 0, 0, 2, 8, 0, 4, 9, 4, 5, 4, 9, 8, 9, 1, 0, 8

Offset: 1

Author

Clark Kimberling, Mar 12 2016

Keywords

• nonn
• cons
• easy

Examples

			1.684813144489576096316554337380078230...
		

Crossrefs

Cf. A000045, A269992.

Cf. A063727, A085449, A103435, A209084.

Programs

Mathematica

x = N[Sum[2^(1 - n)/Fibonacci[n], {n, 1, 500}], 100]
RealDigits[x][[1]]

PARI

suminf(n=1, 2^(1-n)/fibonacci(n)) \\ Michel Marcus, Feb 01 2021

Formula

Equals Sum_{n>=0} 1/A063727(n) = Sum_{n>=1} 1/A085449(n) = 2 * Sum_{n>=1} 1/A103435(n) = 4 * Sum_{n>=1} 1/A209084(n). - Amiram Eldar, Feb 01 2021