A080742 Largest element of n-th row of A080738.

2, 6, 12, 30, 60, 120, 210, 420, 840, 1260, 2520, 2310, 5040, 9240, 13860, 27720, 32760, 55440, 65520, 120120, 180180, 360360, 235620, 720720, 556920, 942480, 1113840, 1531530

Offset

0,1

Links

Table of n, a(n) for n=0..27.

J. Bamberg, G. Cairns and D. Kilminster, The crystallographic restriction, permutations and Goldbach's conjecture, Amer. Math. Monthly, 110 (March 2003), 202-209.

Mathematica

a080737[1] = a080737[2] = 0; a080737[p_?PrimeQ] := a080737[p] = p - 1; a080737[n_] := a080737[n] = If[Length[fi = FactorInteger[n]] == 1, EulerPhi[n], Total[a080737 /@ (fi[[All, 1]]^fi[[All, 2]])]]; orders = Table[{n, a080737[n]}, {n, 1, 2*10^6}]; row[0] = {1, 2}; row[n_] := Select[orders, 2*n - 1 <= #[[2]] <= 2*n &][[All, 1]]; Table[ row[n] // Last, {n, 0, 27}] (* Jean-François Alcover, Jul 24 2013 *)

Prog

(Haskell)
a080742 n k = a080742_list !! n
a080742_list = map last a080738_tabf  -- Reinhard Zumkeller, Jun 13 2012

Crossrefs

Cf. A080737, A080738, A080740, A080741, A005417.

Sequence in context: A133996 A284573 A355475 * A005417 A058215 A330542

Adjacent sequences: A080739 A080740 A080741 * A080743 A080744 A080745

Keyword

nonn,more

Author

N. J. A. Sloane, Mar 08 2003

Extensions

Corrected and extended by Vladeta Jovovic, Mar 09 2003

Status

approved