A061427 Geometric mean of the digits = 3. In other words, the product of the digits is = 3^k where k is the number of digits.

3, 19, 33, 91, 139, 193, 319, 333, 391, 913, 931, 1199, 1339, 1393, 1919, 1933, 1991, 3139, 3193, 3319, 3333, 3391, 3913, 3931, 9119, 9133, 9191, 9313, 9331, 9911, 11399, 11939, 11993, 13199, 13339, 13393, 13919, 13933, 13991, 19139, 19193

Offset: 1

Author

Amarnath Murthy, May 03 2001

Keywords

• nonn
• base
• easy

Examples

			319 is a term as the geometric mean of digits is (3*1*9) = 27 = 3^3.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A061426-A061430.

Cf. A174813.

Programs

Haskell

a061427 n = a061427_list !! (n-1)
a061427_list = g [1] where
   g ds = if product ds == 3 ^ length ds
          then foldr (\d v -> 10 * v + d) 0 ds : g (s ds) else g (s ds)
   s [] = [1]; s (9:ds) = 1 : s ds; s (d:ds) = 3*d : ds
-- Reinhard Zumkeller, Jan 13 2014

Mathematica

Select[Range[20000],GeometricMean[IntegerDigits[#]]==3&] (* Harvey P. Dale, Dec 11 2011 *)

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), May 16 2001