A130509 a(1)=3. a(2)=1. a(3)=2. a(n+3) = 3 + a(n), for all positive integers n.

3, 1, 2, 6, 4, 5, 9, 7, 8, 12, 10, 11, 15, 13, 14, 18, 16, 17, 21, 19, 20, 24, 22, 23, 27, 25, 26, 30, 28, 29, 33, 31, 32, 36, 34, 35, 39, 37, 38, 42, 40, 41, 45, 43, 44, 48, 46, 47, 51, 49, 50, 54, 52, 53, 57, 55, 56, 60, 58, 59, 63, 61, 62, 66, 64, 65, 69, 67

Offset

1,1

Comments

This sequence is the inverse permutation of A130508.

Links

Table of n, a(n) for n=1..68.

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

Formula

a(n) = n - cos(2*n*Pi/3) + sqrt(3)*sin(2*n*Pi/3). - Wesley Ivan Hurt, Sep 26 2017

Sum_{n>=1} (-1)^n/a(n) = log(2)/3. - Amiram Eldar, Jan 31 2023

Mathematica

LinearRecurrence[{1, 0, 1, -1}, {3, 1, 2, 6}, 100] (* Amiram Eldar, Jan 31 2023 *)

Crossrefs

Cf. A130508.

Sequence in context: A080818 A334354 A052417 * A171072 A102035 A055179

Adjacent sequences: A130506 A130507 A130508 * A130510 A130511 A130512

Keyword

easy,nonn

Author

Leroy Quet, Jun 01 2007

Status

approved