login
A101906
Inverse permutation to A101905.
1
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
OFFSET
1,2
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
Sequence in context: A357910 A367082 A039864 * A297403 A120241 A352714
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