cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A290890 p-INVERT of the positive integers, where p(S) = 1 - S^2.

Original entry on oeis.org

0, 1, 4, 11, 28, 72, 188, 493, 1292, 3383, 8856, 23184, 60696, 158905, 416020, 1089155, 2851444, 7465176, 19544084, 51167077, 133957148, 350704367, 918155952, 2403763488, 6293134512, 16475640049, 43133785636, 112925716859, 295643364940, 774004377960
Offset: 0

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Author

Clark Kimberling, Aug 15 2017

Keywords

Comments

Suppose s = (c(0), c(1), c(2), ...) is a sequence and p(S) is a polynomial. Let S(x) = c(0)*x + c(1)*x^2 + c(2)*x^3 + ... and T(x) = (-p(0) + 1/p(S(x)))/x. The p-INVERT of s is the sequence t(s) of coefficients in the Maclaurin series for T(x). Taking p(S) = 1 - S gives the "INVERT" transform of s, so that p-INVERT is a generalization of the "INVERT" transform (e.g., A033453).
Note that in A290890, s = (1,2,3,4,...); i.e., A000027(n+1) for n>=0, whereas in A290990, s = (0,1,2,3,4,...); i.e., A000027(n) for n>=0.
Guide to p-INVERT sequences using s = (1,2,3,4,5,...) = A000027:
p(S) t(1,2,3,4,5,...)
1 - S A001906
1 - S^2 A290890; see A113067 for signed version
1 - S^3 A290891
1 - S^4 A290892
1 - S^5 A290893
1 - S^6 A290894
1 - S^7 A290895
1 - S^8 A290896
1 - S - S^2 A289780
1 - S - S^3 A290897
1 - S - S^4 A290898
1 - S^2 - S^4 A290899
1 - S^2 - S^3 A290900
1 - S^3 - S^4 A290901
1 - 2S A052530; (1/2)*A052530 = A001353
1 - 3S A290902; (1/3)*A290902 = A004254
1 - 4S A003319; (1/4)*A003319 = A001109
1 - 5S A290903; (1/5)*A290903 = A004187
1 - 2*S^2 A290904; (1/2)*A290904 = A290905
1 - 3*S^2 A290906; (1/3)*A290906 = A290907
1 - 4*S^2 A290908; (1/4)*A290908 = A099486
1 - 5*S^2 A290909; (1/5)*A290909 = A290910
1 - 6*S^2 A290911; (1/6)*A290911 = A290912
1 - 7*S^2 A290913; (1/7)*A290913 = A290914
1 - 8*S^2 A290915; (1/8)*A290915 = A290916
(1 - S)^2 A290917
(1 - S)^3 A290918
(1 - S)^4 A290919
(1 - S)^5 A290920
(1 - S)^6 A290921
1 - S - 2*S^2 A290922
1 - 2*S - 2*S^2 A290923; (1/2)*A290923 = A290924
1 - 3*S - 2*S^2 A290925
(1 - S^2)^2 A290926
(1 - S^2)^3 A290927
(1 - S^3)^2 A290928
(1 - S)(1 - S^2) A290929
(1 - S^2)(1 - S^4) A290930
1 - 3 S + S^2 A291025
1 - 4 S + S^2 A291026
1 - 5 S + S^2 A291027
1 - 6 S + S^2 A291028
1 - S - S^2 - S^3 A291029
1 - S - S^2 - S^3 - S^4 A201030
1 - 3 S + 2 S^3 A291031
1 - S - S^2 - S^3 + S^4 A291032
1 - 6 S A291033
1 - 7 S A291034
1 - 8 S A291181
1 - 3 S + 2 S^3 A291031
1 - 3 S + 2 S^2 A291182
1 - 4 S + 2 S^3 A291183
1 - 4 S + 3 S^3 A291184

Examples

			(See the examples at A289780.)
		

Crossrefs

Cf. A000027, A113067, A289780, A113067 (signed version of same sequence).

Programs

  • Mathematica
    z = 60; s = x/(1 - x)^2; p = 1 - s^2;
    Drop[CoefficientList[Series[s, {x, 0, z}], x], 1] (* A000027 *)
    Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1] (* A290890 *)

Formula

G.f.: x/(1 - 4 x + 5 x^2 - 4 x^3 + x^4).
a(n) = 4*a(n-1) - 5*a(n-2) + 4*a(n-3) - a(n-4).