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A143051 Smallest number not occurring earlier and smaller than the largest square so far, the next square if no such number exists. 5
0, 1, 4, 2, 3, 9, 5, 6, 7, 8, 16, 10, 11, 12, 13, 14, 15, 25, 17, 18, 19, 20, 21, 22, 23, 24, 36, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 49, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 64, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 81, 65, 66, 67, 68, 69, 70, 71 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Permutation of the natural numbers, inverse: A143052;

A143053(n) = a(a(n));

a(A000290(n)) = A005563(n-1);

a(A002522(n)) = A000290(n+1);

for n>1: GCD(a(n^2),a(n^2+1)) = A050873(A000290(n),A002522(n)) =

A022998(n+1).

LINKS

Peter Kagey, Table of n, a(n) for n = 0..10000

Index entries for sequences that are permutations of the natural numbers

FORMULA

a(n) = if n=0 then 0 else if n=1+k^2 then n+2*k else n-1.

CROSSREFS

Sequence in context: A016512 A201651 A026246 * A282888 A278101 A120240

Adjacent sequences:  A143048 A143049 A143050 * A143052 A143053 A143054

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jul 20 2008

STATUS

approved

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Last modified January 18 18:48 EST 2018. Contains 297864 sequences.