A074307 Square of permutation in A074305.

0, 2, 3, 1, 11, 5, 7, 13, 6, 4, 10, 19, 9, 27, 21, 15, 29, 14, 8, 18, 35, 17, 43, 37, 23, 45, 22, 12, 26, 51, 25, 59, 53, 31, 61, 30, 16, 34, 67, 33, 75, 69, 39, 77, 38, 20, 42, 83, 41, 91, 85, 47, 93, 46, 24, 50, 99, 49, 107, 101, 55, 109, 54, 28, 58, 115, 57, 123, 117, 63, 125

Offset

0,2

Comments

A permutation of the nonnegative integers.

Links

Table of n, a(n) for n=0..70.

G. Venturini, Iterates of number-theoretic functions with periodic rational coefficients (Generalization of the 3x+1 problem), Stud. Appl. Math., Vol. 86 (1992), pp. 185-218.

Index entries for sequences that are permutations of the natural numbers.

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

Formula

a(9*n)=4*n, a(9*n+1)=8*n+2, a(9*n+2)=16*n+3, a(9*n+3)=8*n+1, a(9*n+4)=16*n+11, a(9*n+5)=16*n+5, a(9*n+6)=8*n+7, a(9*n+7)=16*n+13, a(9*n+8)=8*n+6. - Philippe Deléham, Nov 14 2023

From Elmo R. Oliveira, May 15 2026: (Start)

a(n) = 2*a(n-9) - a(n-18).

G.f.: x*(2 + 3*x + x^2 + 11*x^3 + 5*x^4 + 7*x^5 + 13*x^6 + 6*x^7 + 4*x^8 + 6*x^9 + 13*x^10 + 7*x^11 + 5*x^12 + 11*x^13 + x^14 + 3*x^15 + 2*x^16) / ((x - 1)^2 * (1 + x + x^2)^2 * (1 + x^3 + x^6)^2). (End)

Prog

(PARI) A074305(m) = if(m%3==0, m/3*2, if(m%3==1, (m-1)/3*4+3, (m-2)/3*4+1))
for(i=0, 120, print1(A074305(A074305(i)), ", ")) \\ C. Ronaldo

Crossrefs

Cf. A074305, A074306, A074308.

Sequence in context: A009026 A046222 A291647 * A163486 A214649 A007440

Adjacent sequences: A074304 A074305 A074306 * A074308 A074309 A074310

Keyword

nonn,easy

Author

N. J. A. Sloane, Sep 23 2002

Extensions

More terms from Lambert Klasen (lambert.klasen(AT)gmx.de), Jan 02 2005

Status

approved