login
A116080
Permutation of natural numbers generated by 4-rowed array shown below.
2
0, 4, 1, 8, 5, 2, 12, 9, 6, 3, 16, 13, 10, 7, 20, 17, 14, 11, 24, 21, 18, 15, 28, 25, 22, 19, 32, 29, 26, 23, 36, 33, 30, 27, 40, 37, 34, 31, 44, 41, 38, 35, 48, 45, 42, 39, 52, 49, 46, 43, 56, 53, 50, 47, 60, 57, 54, 51, 64, 61, 58, 55, 68, 65, 62, 59, 72, 69, 66, 63, 76, 73, 70
OFFSET
1,2
COMMENTS
0 4 8 12 16 20 24 28 32 ... a(n) = 4n => A008586;
1 5 9 13 17 21 25 29 33 ... a(n) = 4n+1 => A016813;
2 6 10 14 18 22 26 30 34 ... a(n) = 4n+2 => A016825;
3 7 11 15 19 23 27 31 35 ... a(n) = 4n+3 => A004767.
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
FORMULA
For n > 0, a(n+5) = a(n) + 8 iff a(n+5)<a(n) : a(n+7) = a(n) + 8, iff a(n+7)<a(n): a(n+4k) = a(n) + 4k with k >= 1.
a(n)= a(n-1) + a(n-4) - a(n-5), n>=12. - R. J. Mathar, Apr 22 2010
G.f.: x^2*(4-3*x+7*x^2-3*x^3-7*x^4+13*x^5-10*x^6+3*x^9)/(1-x-x^4+x^5). - Philippe Deléham, Dec 02 2016
MATHEMATICA
LinearRecurrence[{1, 0, 0, 1, -1}, {0, 4, 1, 8, 5, 2, 12, 9, 6, 3, 16}, 80] (* Harvey P. Dale, Feb 20 2022 *)
CROSSREFS
Cf. A115302.
Sequence in context: A141567 A254707 A134417 * A343125 A205296 A143820
KEYWORD
easy,nonn
AUTHOR
Giovanni Teofilatto, Mar 12 2006
EXTENSIONS
Corrected (47 replaced by 41) by R. J. Mathar, Apr 22 2010
STATUS
approved