A269443 Continued fraction expansion of the Dirichlet eta function at 2.

0, 1, 4, 1, 1, 1, 2, 1, 1, 1, 1, 3, 2, 2, 4, 1, 1, 1, 1, 1, 1, 4, 1, 6, 3, 7, 1, 7, 3, 3, 2, 4, 2, 2, 1, 1, 2, 1, 1, 3, 2, 1, 5, 1, 3, 1, 2, 1, 1, 13, 40, 1, 1, 1, 48, 211, 4, 91, 1, 16, 9, 1, 10, 8, 2, 4, 1, 2, 3, 2, 1, 1, 13, 3, 1, 2, 2, 1, 3, 1, 18, 2, 1, 1, 1, 5, 3, 7, 1, 1, 21, 1, 6, 4, 1, 1, 2, 1, 3, 2

Offset: 0

Author

Ilya Gutkovskiy, Feb 26 2016

Keywords

• nonn
• cofr

Comments

Continued fraction expansion of Sum_{k>=1} (-1)^(k-1)/k^2 = Zeta(2)/2 = Pi^2/12 = 0.8224670334241132182362...

Examples

			1/1^2 - 1/2^2 + 1/3^2 - 1/4^2 + 1/5^2 - 1/6^2 +... = 1/(1 + 1/(4 + 1/(1 + 1/(1 + 1/(1 + 1/(2 + 1/...)))))).
		

Links

• OEIS Wiki, Euler's alternating zeta function
• Eric Weisstein's World of Mathematics, Dirichlet Eta Function
• Wikipedia, Dirichlet Eta Function
• Index entries for continued fractions for constants

Crossrefs

Cf. A013679, A072691.

Programs

Mathematica

ContinuedFraction[Pi^2/12, 100]

PARI

contfrac(Pi^2/12) \\ Michel Marcus, Feb 26 2016