login
This site is supported by donations to The OEIS Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A100342 Numerators of the convergents in the continued fraction expansion for twice the constant given by A100338, where the partial quotients equal A006519 (greatest power of 2 dividing n) interleaved with 2's. 4
2, 3, 8, 19, 46, 65, 176, 769, 1714, 2483, 6680, 15843, 38366, 54209, 146784, 1228481, 2603746, 3832227, 10268200, 24368627, 59005454, 83374081, 225753616, 986388545, 2198530706, 3184919251, 8568369208, 20321657667, 49211684542 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The convergents for the continued fraction of x are given by A100340(n)/A100341(n) and the convergents for the continued fraction of 2*x are given by A100342(n)/A100343(n), where A100342(n)/A100343(n) = 2*A100340(n)/A100341(n) for all n.

LINKS

Table of n, a(n) for n=1..29.

FORMULA

a(1) = 2, a(2) = 3; a(2*n) = a(2*n-1)*A006519(n) + a(2*n-2) for n>1, a(2*n-1) = 2*a(2*n-2) + a(2*n-3) for n>1.

EXAMPLE

The constant is 2*x=2.707742256859764748777788168033216248454666833624237..

contfrac(2*x) = [2;1, 2,2, 2,1, 2,4, 2,1, 2,2, 2,1, 2,8,... 2, A006519(n),... ].

PROG

(PARI) {a(n)=if(n==1, 2, if(n==2, 3, if(n%2==1, 2*a(n-1)+a(n-2), a(n-1)*2^valuation(n/2, 2)+a(n-2))))}

CROSSREFS

Cf. A100338, A006519, A100340, A100341, A100343.

Sequence in context: A041205 A002356 A166302 * A041281 A078343 A148038

Adjacent sequences:  A100339 A100340 A100341 * A100343 A100344 A100345

KEYWORD

cofr,nonn

AUTHOR

Paul D. Hanna, Nov 18 2004

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 18 01:36 EST 2019. Contains 319260 sequences. (Running on oeis4.)