A083548 Least common multiple of cototient values of consecutive integers.

0, 1, 2, 2, 4, 4, 4, 12, 6, 6, 8, 8, 8, 56, 56, 8, 12, 12, 12, 36, 36, 12, 16, 80, 70, 126, 144, 16, 22, 22, 16, 208, 234, 198, 264, 24, 20, 60, 120, 24, 30, 30, 24, 168, 168, 24, 32, 224, 210, 570, 532, 28, 36, 180, 480, 672, 210, 30, 44, 44, 32, 864, 864, 544, 782, 46, 36

Offset: 1

Author

Labos Elemer, May 22 2003

Keywords

• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A051953, A083538-A083555, A049586.

Programs

Mathematica

f[x_] := x-EulerPhi[x] Table[LCM[f[w+1], f[w]], {w, 1, b}]
LCM@@#&/@Partition[Table[n-EulerPhi[n],{n,70}],2,1] (* Harvey P. Dale, Feb 01 2015 *)

PARI

a(n)=lcm(n-eulerphi(n),n+1-eulerphi(n+1)) \\ Charles R Greathouse IV, Nov 16 2012

Formula

a(n) = lcm(A051953(n), A051953(n+1)).