A075384 Initial term of n-th group in A075383.

1, 2, 3, 8, 5, 18, 7, 32, 27, 50, 11, 84, 13, 98, 75, 128, 17, 162, 19, 200, 147, 242, 23, 312, 125, 338, 243, 392, 29, 510, 31, 512, 363, 578, 245, 684, 37, 722, 507, 920, 41, 882, 43, 968, 765, 1058, 47, 1392, 343, 1250, 867, 1352, 53, 1458, 605, 1624, 1083, 1682, 59, 2220, 61, 1922, 1449, 2368, 845

Offset: 1

Author

Amarnath Murthy, Sep 22 2002

Keywords

• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A075383, A075385, A075386, A075387, A075388.

Programs

Haskell

a075384 = head . a075383_row  -- Reinhard Zumkeller, Nov 29 2015

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 *)

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