cp's OEIS Frontend

A061426 Geometric mean of the digits = 2. In other words, the product of the digits is = 2^k where k is the number of digits.

%I A061426 #9 Jan 19 2023 01:41:24
%S A061426 2,14,22,41,118,124,142,181,214,222,241,412,421,811,1128,1144,1182,
%T A061426 1218,1224,1242,1281,1414,1422,1441,1812,1821,2118,2124,2142,2181,
%U A061426 2214,2222,2241,2412,2421,2811,4114,4122,4141,4212,4221,4411,8112,8121,8211
%N A061426 Geometric mean of the digits = 2. In other words, the product of the digits is = 2^k where k is the number of digits.
%H A061426 Reinhard Zumkeller, <a href="/A061426/b061426.txt">Table of n, a(n) for n = 1..10000</a>
%e A061426 124 is a term as the geometric mean of digits is (1*2*4) = 8 = 2^3.
%o A061426 (Haskell)
%o A061426 a061426 n = a061426_list !! (n-1)
%o A061426 a061426_list = g [1] where
%o A061426    g ds = if product ds == 2 ^ length ds
%o A061426           then foldr (\d v -> 10 * v + d) 0 ds : g (s ds) else g (s ds)
%o A061426    s [] = [1]; s (8:ds) = 1 : s ds; s (d:ds) = 2*d : ds
%o A061426 -- _Reinhard Zumkeller_, Jan 13 2014
%Y A061426 Cf. A061427-A061430. A069512 gives another version.
%Y A061426 Cf. A028846.
%K A061426 nonn,base,easy
%O A061426 1,1
%A A061426 _Amarnath Murthy_, May 03 2001
%E A061426 More terms from _Erich Friedman_, May 08 2001