A075567 Rearrangement of natural numbers by choosing alternately odd and even numbers such that every partial sum is composite.

9, 6, 1, 2, 3, 4, 5, 8, 7, 10, 11, 12, 13, 14, 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

1,1

Comments

a(n) = n for n > 9.

Links

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

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

Mathematica

LinearRecurrence[{2, -1}, {9, 6, 1, 2, 3, 4, 5, 8, 7, 10, 11}, 80] (* Harvey P. Dale, Apr 21 2025 *)

Prog

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

Crossrefs

Cf. A075566.

Sequence in context: A011114 A298243 A020783 * A019883 A085574 A194825

Adjacent sequences: A075564 A075565 A075566 * A075568 A075569 A075570

Keyword

nonn,easy

Author

Amarnath Murthy, Sep 25 2002

Extensions

Extended by Ray Chandler, Feb 13 2005

Status

approved