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A075380 Rearrangement of natural numbers so that the sum of two neighboring terms is not squarefree. 8
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 (list; graph; refs; listen; history; text; internal format)
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

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

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: A210195 A069918 A200700 * A248497 A255439 A177983

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

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Last modified March 20 20:14 EDT 2019. Contains 321352 sequences. (Running on oeis4.)