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A147657
a(1)=1, a(2)=2, thereafter (1, -2, 3, -4, 5, -6, ...) interleaved with (-2, 2, -2, 2, ...).
3
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.
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
Sequence in context: A211976 A035460 A261679 * A029232 A221531 A282970
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