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

1,1

Links

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

Example

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

Mathematica

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

Prog

(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

Crossrefs

Cf. A061426-A061430.

Cf. A174813.

Sequence in context: A128069 A056246 A360081 * A069516 A098856 A178201

Adjacent sequences: A061424 A061425 A061426 * A061428 A061429 A061430

Keyword

nonn,base,easy

Author

Amarnath Murthy, May 03 2001

Extensions

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

Status

approved