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.

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A329975 Beatty sequence for 1 + x + x^2, where x is the real solution of 1/x + 1/(1+x+x^2) = 1.

Original entry on oeis.org

4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 53, 57, 61, 65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 106, 110, 114, 118, 122, 126, 130, 134, 138, 142, 146, 150, 155, 159, 163, 167, 171, 175, 179, 183, 187, 191, 195, 199, 203, 208, 212, 216, 220, 224, 228, 232
Offset: 1

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Author

Clark Kimberling, Jan 02 2020

Keywords

Comments

Let x be the real solution of 1/x + 1/(1+x+x^2) = 1. Then (floor(n*x)) and (floor(n*(x^2 + x + 1))) are a pair of Beatty sequences; i.e., every positive integer is in exactly one of the sequences. See the Guide to related sequences at A329825.

Crossrefs

Cf. A329825, A060006, A329974 (complement).

Programs

  • Mathematica
    Solve[1/x + 1/(1 + x + x^2) == 1, x]
    u = 1/3 (27/2 - (3 Sqrt[69])/2)^(1/3) + (1/2 (9 + Sqrt[69]))^(1/3)/3^(2/3);
    u1 = N[u, 150]
    RealDigits[u1, 10][[1]]  (* A060006 *)
    Table[Floor[n*u], {n, 1, 50}]              (* A329974 *)
    Table[Floor[n*(1 + u + u^2)], {n, 1, 50}]  (* A329975 *)
    Plot[1/x + 1/(1 + x + x^2) - 1, {x, -2, 2}]

Formula

a(n) = floor(n*(1+x+x^2)), where x = 1.324717... is the constant in A060006.
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