Number of distinct denominators of rational numbers whose continued fraction consists exclusively of 1s and 2s and has length <=n.

A228805

Number of distinct denominators of rational numbers whose continued fraction consists exclusively of 1s and 2s and has length <=n.

Terms

    a(0) =1a(1) =2a(2) =4a(3) =8a(4) =14a(5) =26a(6) =45a(7) =85a(8) =155a(9) =286a(10) =540a(11) =1047a(12) =2014a(13) =3939a(14) =7642a(15) =15082a(16) =29601a(17) =58797a(18) =116248a(19) =231530a(20) =459976a(21) =917030a(22) =1826669a(23) =3641525a(24) =7253511a(25) =14463688a(26) =28834305a(27) =57481793a(28) =114543879a(29) =228286471

External references