OFFSET
1,2
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
MAPLE
A075383 := proc(nmax) local a, n, ct, k; a := [1, 2, 4] ; for n from 3 do ct := 0 ; for k from 1 do if (k*n) in a then ; else a := [op(a), k*n] ; ct := ct+1 ; if ct >= n then break ; fi ; fi; od: if nops(a) > nmax then RETURN(a) ; fi; od: end: A075384 := proc(n, a075383) local i, k ; i := 1 ; for k from 1 to n-1 do i := i+k ; if i > nops(a075383) then RETURN(-1) ; fi; od: RETURN(op(i, a075383)) ; end: a075383 := A075383(4000) : for n from 1 to 70 do a084 := A075384(n, a075383) ; if a084 < 0 then break; else printf("%d, ", a084) ; fi; od:
MATHEMATICA
row[n_] := row[n] = If[n == 1, {1}, rows = Join[row /@ Range[n-1]]; ro = {}; For[k = n, Length[ro] < n, k = k + n, If[FreeQ[rows, k], AppendTo[ro, k]]]; ro]; a[n_] := row[n][[1]]; Array[a, 65] (* Jean-François Alcover, Jan 27 2018 *)
PROG
(Haskell)
a075384 = head . a075383_row -- Reinhard Zumkeller, Nov 29 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Sep 22 2002
EXTENSIONS
More terms from Reinhard Zumkeller, Jul 09 2004
Removed claim on relation to A096776. Corrected from a(20) on by R. J. Mathar, Oct 31 2008
STATUS
approved