A033466 Denominators of the first differences of 1/(n^2 + 1).

2, 10, 10, 170, 442, 962, 1850, 650, 5330, 8282, 12322, 17690, 986, 33490, 44522, 58082, 74530, 18850, 117650, 145162, 177242, 214370, 51410, 305810, 361202, 423802, 494210, 114610, 660970, 758642

Offset

0,1

Links

G. C. Greubel, Table of n, a(n) for n = 0..2000

Formula

For all n not in A016873, a(n) = n^4 + 2n^3 + 3n^2 + 2n + 2, else A099024((n-2)/5). - Ralf Stephan, Sep 25 2004

a(n) = denominator of (2*n+1)/((n^2+1)*((n+1)^2+1)). - G. C. Greubel, Oct 14 2024

Mathematica

Table[Denominator[(1+2*n)/((1+n^2)*(1+(n+1)^2))], {n, 0, 40}] (* G. C. Greubel, Oct 14 2024 *)

Prog

(Magma)
A033466:= func< n | Denominator((2*n+1)/((n^2+1)*((n+1)^2+1))) >;
[A033466(n): n in [0..40]]; // G. C. Greubel, Oct 14 2024
(SageMath)
def A033466(n): return denominator((2*n+1)/((n^2+1)*((n+1)^2+1)))
[A033466(n) for n in range(41)] # G. C. Greubel, Oct 14 2024

Crossrefs

Cf. A033465 (numerators).

Sequence in context: A066394 A232500 A351659 * A193181 A338401 A222638

Adjacent sequences: A033463 A033464 A033465 * A033467 A033468 A033469

Keyword

nonn,frac

Author

N. J. A. Sloane

Status

approved