A195503 Numerators b(n) of Pythagorean approximations b(n)/a(n) to sqrt(3).

4, 15, 56, 209, 780, 2911, 10864, 40545, 151316, 564719, 2107560, 7865521, 29354524, 109552575, 408855776, 1525870529, 5694626340, 21252634831, 79315912984, 296011017105, 1104728155436, 4122901604639, 15386878263120, 57424611447841

Offset

1,1

Comments

See A195500 for discussion and list of related sequences; see A195499 for Mathematica program.

Essentially the same as A001353, A106707, A125905 and likely also A010905. - R. J. Mathar, Sep 21 2011

If started 1, 4, 15, 56, ...., denominators a(n) of Pythagorean approximations b(n)/a(n) to sqrt(1/3). - Clark Kimberling, Sep 22 2011

Links

Table of n, a(n) for n=1..24.

Index entries for linear recurrences with constant coefficients, signature (4, -1).

Formula

a(n) = A001353(n+1). - R. J. Mathar, Sep 21 2011

Empirical G.f.: x*(4-x)/(1-4*x+x^2). - Colin Barker, Jan 04 2012

Crossrefs

Cf. A195500, A195499, A195531.

Sequence in context: A221859 A106707 A125905 * A001353 A010905 A026030

Adjacent sequences: A195500 A195501 A195502 * A195504 A195505 A195506

Keyword

nonn,easy

Author

Clark Kimberling, Sep 20 2011

Status

approved