The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A164000 Main diagonal of array in A163280. 14
 1, 6, 15, 28, 45, 66, 91, 128, 162, 200, 231, 372, 325, 406, 495, 656, 561, 954, 703, 1180, 987, 1078, 1035, 1896, 1375, 1534, 1701, 2324, 1653, 3090, 1891, 3104, 2541, 2686, 3045, 5004, 2701, 3382, 3627, 5560, 3321, 6846, 3655, 6028, 6165, 5014, 4371 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS MAPLE A033676 := proc(n) local a, d; a := 0 ; for d in numtheory[divisors](n) do if d^2 <= n then a := max(a, d) ; end if; end do: a; end proc: A163280 := proc(n, k) local r, T ; r := 0 ; for T from k^2 by k do if A033676(T) = k then r := r+1 ; if r = n then RETURN(T) ; end if; end if; end do: end proc: A164000 := proc(n) A163280(n, n) ; end proc: seq(A164000(n), n=1..60) ; # R. J. Mathar, Feb 16 2010 MATHEMATICA nmax = 50; pm = Prime[nmax]; selDiv[n_] := Select[Divisors[n], #^2 <= n&][[-1]]; Clear[col]; col[k_] := col[k] = Select[Range[k pm], selDiv[#] == k&]; a[n_] := col[n][[n]]; Array[a, nmax] (* Jean-François Alcover, Mar 24 2020 *) CROSSREFS Cf. A008578, A161344, A161345, A163280. Sequence in context: A081873 A096892 A000384 * A212087 A301292 A134978 Adjacent sequences:  A163997 A163998 A163999 * A164001 A164002 A164003 KEYWORD nonn AUTHOR Omar E. Pol, Aug 08 2009 EXTENSIONS Terms from a(13) on by R. J. Mathar, Feb 16 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified July 31 15:25 EDT 2021. Contains 346374 sequences. (Running on oeis4.)