A075380 Rearrangement of natural numbers so that the sum of two neighboring terms is not squarefree.

1, 3, 5, 4, 8, 10, 2, 6, 12, 13, 7, 9, 11, 14, 18, 22, 23, 17, 15, 21, 19, 25, 20, 16, 24, 26, 28, 32, 31, 29, 27, 33, 30, 34, 38, 37, 35, 40, 36, 39, 41, 43, 45, 47, 49, 50, 42, 46, 44, 48, 51, 53, 55, 57, 59, 58, 54, 62, 63, 61, 56, 52, 60, 64, 68, 67, 65, 70, 66, 69, 71, 73

Offset

1,2

Comments

Lexicographically earliest permutation of the natural numbers with the defining property; inverse: A167902; A167901(n) = a(a(n)). [Reinhard Zumkeller, Nov 15 2009]

Links

Scott R. Shannon, Table of n, a(n) for n = 1..10000

Index entries for sequences that are permutations of the natural numbers [Reinhard Zumkeller, Nov 15 2009]

Prog

(PARI) v=[1]; n=1; while(n<100, if(!issquarefree(v[#v]+n)&&!vecsearch(vecsort(v), n), v=concat(v, n); n=0); n++); v \\ Derek Orr, Jun 08 2015

Crossrefs

Cf. A075381.

Cf. A167903, A121878. [Reinhard Zumkeller, Nov 15 2009]

Sequence in context: A361709 A200700 A356377 * A349374 A248497 A255439

Adjacent sequences: A075377 A075378 A075379 * A075381 A075382 A075383

Keyword

nonn

Author

Amarnath Murthy, Sep 22 2002

Extensions

More terms from David Wasserman, Jan 17 2005

Status

approved