A107788 Numbers of the form (8^i)*(11^j), with i, j >= 0.

1, 8, 11, 64, 88, 121, 512, 704, 968, 1331, 4096, 5632, 7744, 10648, 14641, 32768, 45056, 61952, 85184, 117128, 161051, 262144, 360448, 495616, 681472, 937024, 1288408, 1771561, 2097152, 2883584, 3964928, 5451776, 7496192, 10307264

Offset: 1

Author

Douglas Winston (douglas.winston(AT)srupc.com), Jun 14 2005

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A025633, A025634, A107764, A003596, A003597, A107988, A003598, A003599, A108090.

Programs

Haskell

import Data.Set (singleton, deleteFindMin, insert)
a107788 n = a107788_list !! (n-1)
a107788_list = f $ singleton (1,0,0) where
   f s = y : f (insert (8 * y, i + 1, j) $ insert (11 * y, i, j + 1) s')
         where ((y, i, j), s') = deleteFindMin s
-- Reinhard Zumkeller, May 15 2015

Mathematica

Take[Union[8^First[#]*11^Last[#]&/@Tuples[Range[0,20],2]],40] (* Harvey P. Dale, Jan 17 2015 *)
n = 10^6; Flatten[Table[8^i*11^j, {i, 0, Log[8, n]}, {j, 0, Log[11, n/8^i]}]] // Sort (* Amiram Eldar, Oct 07 2020 *)

Formula

Sum_{n>=1} 1/a(n) = (8*11)/((8-1)*(11-1)) = 44/35. - Amiram Eldar, Oct 07 2020

a(n) ~ exp(sqrt(2*log(8)*log(11)*n)) / sqrt(88). - Vaclav Kotesovec, Oct 07 2020