This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A075384 #12 Jan 27 2018 13:28:05
%S A075384 1,2,3,8,5,18,7,32,27,50,11,84,13,98,75,128,17,162,19,200,147,242,23,
%T A075384 312,125,338,243,392,29,510,31,512,363,578,245,684,37,722,507,920,41,
%U A075384 882,43,968,765,1058,47,1392,343,1250,867,1352,53,1458,605,1624,1083,1682,59,2220,61,1922,1449,2368,845
%N A075384 Initial term of n-th group in A075383.
%H A075384 Reinhard Zumkeller, <a href="/A075384/b075384.txt">Table of n, a(n) for n = 1..1000</a>
%p A075384 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:
%t A075384 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 *)
%o A075384 (Haskell)
%o A075384 a075384 = head . a075383_row -- _Reinhard Zumkeller_, Nov 29 2015
%Y A075384 Cf. A075383, A075385, A075386, A075387, A075388.
%K A075384 nonn
%O A075384 1,2
%A A075384 _Amarnath Murthy_, Sep 22 2002
%E A075384 More terms from _Reinhard Zumkeller_, Jul 09 2004
%E A075384 Removed claim on relation to A096776. Corrected from a(20) on by _R. J. Mathar_, Oct 31 2008