A115659 Permutation of natural numbers generated by 2-rowed array shown below.

0, 3, 1, 4, 2, 7, 5, 8, 6, 11, 9, 12, 10, 15, 13, 16, 14, 19, 17, 20, 18, 23, 21, 24, 22, 27, 25, 28, 26, 31, 29, 32, 30, 35, 33, 36, 34, 39, 37, 40, 38, 43, 41, 44, 42, 47, 45, 48, 46, 51, 49, 52, 50, 55, 53, 56, 54, 59, 57, 60, 58, 63, 61, 64, 62

Offset

1,2

Comments

0 3 4 7 8 11 12 15 ...: integers congruent to 0 or 3 mod 4.

1 2 5 6 9 10 13 14 ...: integers congruent to 1 or 2 mod 4.

References

M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988

Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta, UTET, CittaStudiEdizioni, Milano 1997

Links

Table of n, a(n) for n=1..65.

Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).

Formula

For n>0, a(n+4k) = a(n) + 4k, with k>=0.

G.f.: x^2*(3 - 2*x + 3*x^2 - 2*x^3 + 2*x^4)/(1 - x - x^4 + x^5). - Philippe Deléham, Dec 02 2016

Mathematica

Join[{0}, LinearRecurrence[{1, 0, 0, 1, -1}, {3, 1, 4, 2, 7}, 70]] (* Vincenzo Librandi, Dec 02 2016 *)

Prog

I:=[0, 3, 1, 4, 2, 7]; [n le 6 select I[n] else Self(n-1)+Self(n-4)-Self(n-5): n in [1..70]]; // Vincenzo Librandi, Dec 02 2016

Crossrefs

Cf. A090964.

Sequence in context: A273261 A274531 A365434 * A067060 A068028 A240058

Adjacent sequences: A115656 A115657 A115658 * A115660 A115661 A115662

Keyword

easy,nonn

Author

Giovanni Teofilatto, Mar 18 2006

Extensions

Entries corrected by R. J. Mathar, Oct 25 2011

Status

approved