A007479 Earliest sequence with a(a(a(n))) = 2n.

0, 3, 6, 5, 12, 2, 10, 9, 24, 11, 4, 14, 20, 15, 18, 17, 48, 26, 22, 21, 8, 23, 28, 38, 40, 27, 30, 29, 36, 50, 34, 33, 96, 35, 52, 62, 44, 39, 42, 41, 16, 74, 46, 45, 56, 47, 76, 86, 80, 51, 54, 53, 60, 98, 58, 57, 72, 59, 100, 110, 68, 63, 66, 65

Offset: 0

Author

N. J. A. Sloane

Keywords

• easy
• nonn
• nice

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Delbert L. Johnson, Table of n, a(n) for n = 0..19999
• Index entries for sequences of the a(a(n)) = 2n family

Crossrefs

Cf. A002516.

Formula

a(0) = 0, a(2*n) = 2*a(n), a(6*n+1) = 6*n+3, a(6*n+3) = 6*n+5, a(6*n+5) = 12*n+2. - Sean A. Irvine, Jan 05 2018

Extensions

Missing a(48) = 80 inserted by Sean A. Irvine, Jan 05 2018