A101906 - OEIS

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A101906

Inverse permutation to A101905.

1, 2, 4, 3, 6, 8, 10, 5, 7, 12, 14, 16, 18, 11, 20, 9, 22, 24, 15, 26, 13, 28, 30, 19, 32, 34, 36, 38, 40, 23, 42, 17, 44, 21, 46, 27, 48, 50, 52, 31, 54, 56, 58, 35, 25, 60, 29, 62, 64, 66, 39, 68, 70, 72, 74, 43, 76, 78, 37, 80, 47, 82, 84, 33, 86, 88, 51, 90, 92, 94, 96, 55

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OFFSET

1,2

LINKS

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

MAPLE

A101261 := proc(nmax) local a, n, anex ; a := [1, 2] ; while nops(a) < nmax do if nops(a) mod 2 = 0 then a := [op(a), 1] ; else n := (nops(a)+1)/2 ; n := op(n, a) ; anex := 2 ; while anex in a or n > 1 do if not anex in a then n := n-1 ; fi ; anex := anex+1 ; od ; a := [op(a), anex] ; fi ; od ; RETURN(a) ; end: A101905 := proc(nmax) local a, n, anex ; a := A101261(2*nmax) ; for n from 2*nmax-1 to 3 by -2 do a := subsop(n=NULL, a) ; od ; RETURN(a) ; end: a := A101905(80) ; n:= 1: while member(n, a, 'ninv') do printf("%d, ", ninv) ; n := n+1 : od : # R. J. Mathar, May 02 2007

CROSSREFS

Cf. A101261, A101905.

Sequence in context: A357910 A367082 A039864 * A297403 A120241 A352714

Adjacent sequences: A101903 A101904 A101905 * A101907 A101908 A101909

KEYWORD

easy,less,nonn

AUTHOR

Leroy Quet, Dec 20 2004

EXTENSIONS

More terms from R. J. Mathar, May 02 2007

More terms from David Wasserman, Mar 31 2008

STATUS

approved