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A119810 Partial quotients of the continued fraction of the constant defined by binary sums involving Beatty sequences: c = Sum_{n>=1} 1/2^A049472(n) = Sum_{n>=1} A001951(n)/2^n. 1
2, 3, 10, 132, 131104, 2199023259648, 633825300114114700748888473600, 883423532389192164791648750371459257913741948437810659652423818057613312 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Convergents A119811: [2/1,7/3,72/31,9511/4095,1246930216/536870911,...], where the denominators of the convergents are equal to [2^A000129(n-1)-1] and A000129 is the Pell numbers. The number of digits in these partial quotients are (beginning at n=1): [1,1,2,3,6,13,30,72,174,420,1013,2445,5901,14246,34391,83027,...].

FORMULA

a(n) = 2^A001333(n-1) + 2^A000129(n-2) for n>1, with a(1)=2.

EXAMPLE

c = 2.32258852258806773012144068278798408011950250800432925665718...

The partial quotients start:

a(1) = 2^1; a(2) = 2^1 + 2^0; a(3) = 2^3 + 2^1;

a(4) = 2^7 + 2^2; a(5) = 2^17 + 2^5; a(6) = 2^41 + 2^12;

and continue as a(n) = 2^A001333(n-1) + 2^A000129(n-2) where

A001333(n) = ( (1+sqrt(2))^n + (1-sqrt(2))^n )/2;

A000129(n) = ( (1+sqrt(2))^n - (1-sqrt(2))^n )/(2*sqrt(2)).

PROG

(PARI) {a(n)=if(n==1, 2, 2^round(((1+sqrt(2))^(n-1)+(1-sqrt(2))^(n-1))/2) +2^round(((1+sqrt(2))^(n-2)-(1-sqrt(2))^(n-2))/(2*sqrt(2))))}

CROSSREFS

Cf. A119809 (decimal expansion), A119811 (convergents); A119812 (dual constant).

Sequence in context: A076927 A064647 A062006 * A055708 A162647 A132536

Adjacent sequences:  A119807 A119808 A119809 * A119811 A119812 A119813

KEYWORD

cofr,nonn

AUTHOR

Paul D. Hanna (pauldhanna(AT)juno.com), May 26 2006

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Last modified February 17 10:57 EST 2012. Contains 206009 sequences.