A147657 a(1)=1, a(2)=2, thereafter (1, -2, 3, -4, 5, -6, ...) interleaved with (-2, 2, -2, 2, ...).

1, 2, 1, -2, -2, 2, 3, -2, -4, 2, 5, -2, -6, 2, 7, -2, -8, 2, 9, -2, -10, 2, 11, -2, -12, 2, 13, -2, -14, 2, 15, -2, -16, 2, 17, -2, -18, 2, 19, -2, -20, 2, 21, -2, -22, 2, 23, -2, -24, 2, 25, -2, -26, 2, 27, -2, -28, 2, 29, -2, -30, 2, 31, -2, -32, 2, 33

Offset

1,2

Comments

Equals POLYMOTZKINTINV [1,2,3,...], such that POLYMOTZKINT A147657 = [1,2,3,...]. A comment accompanying the POLYMOTZKINT operation may be found in A005717.

Links

Table of n, a(n) for n=1..67.

Index entries for linear recurrences with constant coefficients, signature (0,-2,0,-1).

Formula

(1, -2, 3, -4, 5,...) interleaved with (1, 2, -2, 2,...) such that the first subsequence starts after the first "2" in the second subsequence.

G.f.: x + x^2*(2+x+2*x^2)/(1+x^2)^2. - R. J. Mathar, Dec 13 2022

Mathematica

Join[{1, 2}, LinearRecurrence[{0, -2, 0, -1}, {1, -2, -2, 2}, 65]] (* Georg Fischer, Nov 02 2021 *)

Crossrefs

Cf. A005717, A147658.

Sequence in context: A211976 A035460 A261679 * A029232 A221531 A282970

Adjacent sequences: A147654 A147655 A147656 * A147658 A147659 A147660

Keyword

easy,sign

Author

Gary W. Adamson, Nov 09 2008

Extensions

Definition and a(28) ff. corrected by Georg Fischer, Nov 02 2021

Status

approved