

A092486


Take natural numbers, exchange first and third quadrisection.


8



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

0,1


LINKS

Harry J. Smith, Table of n, a(n) for n = 0..20003
Index entries for sequences that are permutations of the natural numbers
Index entries for linear recurrences with constant coefficients, signature (2,2,2,1).


FORMULA

G.f.: (34*x+3*x^2)/((1+x^2)*(1x)^2).
a(4n) = 4n+3, a(4n+1) = 4n+2, a(4n+2) = 4n+1, a(4n+3) = 4n+4.
a(n) = n+1+i^n+(i)^n, where i is the imaginary unit.  Bruno Berselli, Feb 08 2011
From Wesley Ivan Hurt, May 09 2021: (Start)
a(n) = 2*a(n1)2*a(n2)+2*a(n3)a(n4).
a(n) = 1 + n + 2*cos(n*Pi/2). (End)


MATHEMATICA

Flatten[Partition[Range[80], 4]/.{a_, b_, c_, d_}>{c, b, a, d}] (* Harvey P. Dale, Aug 12 2012 *)


PROG

(PARI) { f="b092486.txt"; for (n=0, 5000, a0=4*n + 3; a1=a0  1; a2=a1  1; a3=a0 + 1; write(f, 4*n, " ", a0); write(f, 4*n+1, " ", a1); write(f, 4*n+2, " ", a2); write(f, 4*n+3, " ", a3); ); } \\ Harry J. Smith, Jun 21 2009]


CROSSREFS

Cf. A080412, A064429, A074066, A080782, A159966.
Sequence in context: A117212 A208153 A105033 * A159966 A119263 A028412
Adjacent sequences: A092483 A092484 A092485 * A092487 A092488 A092489


KEYWORD

nonn,easy


AUTHOR

Ralf Stephan, Apr 04 2004


STATUS

approved



