A099135 a(n) = smallest number m, not occurring earlier, such that a(k)+m is a square for some k<n; a(1) = 1.

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

Offset

1,2

Comments

Permutation of the natural numbers with inverse A099136;

a(n) <> n iff 1 < n <= 14.

Links

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

Index entries for sequences that are permutations of the natural numbers

Index entries for linear recurrences with constant coefficients, signature (2,-1).

Prog

(PARI) a(n)=if(n>14, n, [1, 3, 6, 8, 10, 13, 12, 4, 5, 11, 14, 2, 7, 9][n]) \\ Charles R Greathouse IV, Sep 02 2011

Crossrefs

Cf. A048761, A068527.

Sequence in context: A257874 A180398 A128420 * A323028 A189471 A169863

Adjacent sequences: A099132 A099133 A099134 * A099136 A099137 A099138

Keyword

nonn,easy

Author

Reinhard Zumkeller, Sep 29 2004

Status

approved