A115302 Permutation of natural numbers generated by 3-rowed array shown below.

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

Offset: 1

Author

Giovanni Teofilatto, Mar 05 2006

Keywords

• easy
• nonn

Comments

1 4 7 10 13 16 19 22 25...a(n)=3n+1 => A016777

2 5 8 11 14 17 20 23 26...a(n)=3n+2 => A016789

3 6 9 12 15 18 21 24 27...a(n)=3n => A008585

Reversing the direction of the diagonals gives A143097. - Jeremy Gardiner, Oct 14 2012.

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

Crossrefs

Cf. A088520, A090243, A090298, A143097.

Formula

For n > 1, a(n+5) = a(n) + 6, iff a(n+5)=1.