A128296 a(n) = denominator of b(n): b(1)=1; b(n+1) = b(n) * [b(1);b(2),...,b(n)], where [...] is a continued fraction of rational terms.

1, 1, 1, 3, 99, 1917729, 695291630330558547, 2868367896364283363830544991834226772439236224131

Offset

1,4

Comments

a(9) and a(10) have 129 and 341 digits, respectively and are too large to include here. - R. J. Mathar, Oct 08 2007

Links

Table of n, a(n) for n=1..8.

Example

a(5) = the denominator of b(5). b(5) = (10/3) * (1 +1/(1 +1/(2 +3/10))) = 560/99.

Maple

L2cfrac := proc(L) local a, i; a := op(-1, L) ; for i from 2 to nops(L) do a := op(-i, L)+1/a ; od: RETURN(a) ; end: A128296 := proc() local b, n, bnxt; b := [1] ; for n from 2 to 10 do bnxt := op(-1, b)*L2cfrac(b) ; b := [op(b), bnxt] ; od: [seq( denom(b[i]), i=1..nops(b))] ; end: A128296() ; # R. J. Mathar, Oct 08 2007

Crossrefs

Cf. A128295.

Sequence in context: A180350 A293952 A303826 * A037114 A336437 A069457

Adjacent sequences: A128293 A128294 A128295 * A128297 A128298 A128299

Keyword

frac,nonn

Author

Leroy Quet, Feb 25 2007

Extensions

More terms from R. J. Mathar, Oct 08 2007

Status

approved