A161559 Engel expansion of tan(1/2).

2, 11, 54, 136, 1473, 3483, 36244, 41086, 305728, 379955, 582669, 4540387, 5020443, 22096761, 24228660, 48364856, 178868536, 234516235, 524137295, 1096104266, 11627672572, 19828856452, 31372689367, 47247829739, 701124643395

Offset

1,1

Links

Table of n, a(n) for n=1..25.

Index to sequences related to Engel expansions

Example

A161011 = 0.546302.... = 1/2+1/(2*11)+1/(2*11*54)+1/(2*11*54*136)+ ...

Mathematica

EngelExp[A_, n_]:=Join[Array[1&, Floor[A]], First@Transpose@NestList[{Ceiling[1/ Expand[ #[[1]]#[[2]]-1]], Expand[ #[[1]]#[[2]]-1]}&, {Ceiling[1/(A-Floor[A])], A-Floor[A]}, n-1]]; EngelExp[N[Tan[1/2], 6! ], 50]

Crossrefs

Cf. A006784.

Sequence in context: A289847 A063767 A307568 * A291386 A128748 A251662

Adjacent sequences: A161556 A161557 A161558 * A161560 A161561 A161562

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Jun 13 2009

Extensions

Example added by R. J. Mathar, Oct 04 2009

Status

approved