A108698 Numbers of the form (6^i)*(11^j), with i, j >= 0.

1, 6, 11, 36, 66, 121, 216, 396, 726, 1296, 1331, 2376, 4356, 7776, 7986, 14256, 14641, 26136, 46656, 47916, 85536, 87846, 156816, 161051, 279936, 287496, 513216, 527076, 940896, 966306, 1679616, 1724976, 1771561, 3079296, 3162456

Offset: 1

Author

Douglas Winston (douglas.winston(AT)srupc.com), Jun 19 2005

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A025626, A025627, A025628, A025629, A064476, A107710, A003596, A003597, A107988, A003598, A108687, A003599, A107788, A108090.

Programs

Haskell

import Data.Set (singleton, deleteFindMin, insert)
a108698 n = a108698_list !! (n-1)
a108698_list = f $ singleton (1,0,0) where
   f s = y : f (insert (6 * y, i + 1, j) $ insert (11 * y, i, j + 1) s')
         where ((y, i, j), s') = deleteFindMin s
-- Reinhard Zumkeller, May 15 2015

Mathematica

n = 10^6; Flatten[Table[6^i*11^j, {i, 0, Log[6, n]}, {j, 0, Log[11, n/6^i]}]] // Sort (* Amiram Eldar, Oct 07 2020 *)

Formula

Sum_{n>=1} 1/a(n) = (6*11)/((6-1)*(11-1)) = 33/25. - Amiram Eldar, Oct 07 2020

a(n) ~ exp(sqrt(2*log(6)*log(11)*n)) / sqrt(66). - Vaclav Kotesovec, Oct 07 2020