OFFSET
1,1
COMMENTS
After n steps of the construction process n(n-1)/2 terms have been decided.
LINKS
Ivan Neretin, Table of n, a(n) for n = 1..8001
EXAMPLE
1
2,1,4 (multiples of 2 placed alternately )
2,3,1,6,4,9,(multiples of 3 placed alternately )
2,3,1,8,6,12,4,16,9,20
2,3,1,8,6,12,5,4,10,16,15,9,25,20,30
The next step is to place unused multiples of 6, i.e. 18,24,36,42,48,54 at position marked ##:
2,3,1,8,6,12,5,4,10,16,##,15,##,9,##,25,##,20,##,30,##
...
After the 5th stage the terms 2,3,1,8,6,12,5,4,10,16 remain unchanged, hence form the initial 10 terms of the desired sequence.
MATHEMATICA
mx = 13; a = {2, 1, 4}; Do[d = Complement[Range[Max[a] + 1]*n, a]; a = Join[Drop[a, -n], Riffle[Take[a, -n], Take[d, n]]], {n, 3, mx}]; Take[a, mx (mx - 1)/2] (* Ivan Neretin, Sep 06 2017 *)
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Amarnath Murthy, Jun 18 2004
EXTENSIONS
Extended and edited by John W. Layman, Jun 06 2005
STATUS
approved