A119263 A permutation of the positive integers made by (alternatingly) reversing the order of the squarefree positive integers within each run of squarefree integers and reversing the order of the nonsquarefree positive integers within each run of nonsquarefree integers.

3, 2, 1, 4, 7, 6, 5, 9, 8, 11, 10, 12, 15, 14, 13, 16, 17, 18, 19, 20, 23, 22, 21, 25, 24, 26, 28, 27, 31, 30, 29, 32, 35, 34, 33, 36, 39, 38, 37, 40, 43, 42, 41, 45, 44, 47, 46, 50, 49, 48, 51, 52, 53, 54, 55, 56, 59, 58, 57, 60, 62, 61, 64, 63, 67, 66, 65, 68, 71, 70, 69, 72

Offset

1,1

Comments

Sequence is its own inverse permutation.

Links

Table of n, a(n) for n=1..72.

Example

The run of nonsquarefree integers (27,28) becomes (28,27). And the run of squarefree integers (29,30,31) becomes (31,30,29).

Prog

(PARI) {m=73; n=1; while(n<=m, k=n; while(issquarefree(n), n++); forstep(a=n-1, k, -1, print1(a, ", ")); k=n; while(!issquarefree(n), n++); forstep(a=n-1, k, -1, print1(a, ", ")))} \\ Klaus Brockhaus, Aug 16 2006

Crossrefs

Sequence in context: A105033 A092486 A159966 * A028412 A156699 A245183

Adjacent sequences: A119260 A119261 A119262 * A119264 A119265 A119266

Keyword

nonn

Author

Leroy Quet, Jul 23 2006

Extensions

More terms from Klaus Brockhaus, Aug 16 2006

Status

approved