A147551 Minimum of A000010(m) where m is an n-digit number.

1, 4, 32, 240, 2304, 20736, 184320, 1843200, 17740800, 170311680, 1642291200, 16057958400, 153280512000, 1532805120000, 15229951672320, 147149291520000, 1456777986048000, 14214621560832000, 140724753452236800

Offset

1,2

Links

H. v. Eitzen, Table of n, a(n) for n = 1..31

Formula

a(n) = A000010(A147550(n))

Mathematica

a[n_]:=Min[EulerPhi[Range[10^(n-1), 10^n-1]]]; Do[Print[a[n]], {n, 10}]

Prog

(PARI) a(n)=if(n<3, return(3*n-2)); my(t=eulerphi(10^(n-1))); forstep(k=(10^n\300+1)*30, 10^n, 30, if(eulerphi(k)<t, t=eulerphi(k))); t \\ Charles R Greathouse IV, Feb 21 2013

Crossrefs

Cf. A147550.

Sequence in context: A331334 A301779 A370044 * A316803 A299649 A317520

Adjacent sequences: A147548 A147549 A147550 * A147552 A147553 A147554

Keyword

base,nonn

Author

Farideh Firoozbakht, Nov 23 2008

Extensions

More terms from Hagen von Eitzen, Jun 05 2009

Offsets in b-file corrected by N. J. A. Sloane, Aug 31 2009

Status

approved