cp's OEIS Frontend

A107988 Numbers of the form (4^i)*(11^j), with i, j >= 0.

%I A107988 #13 Sep 24 2020 04:10:28
%S A107988 1,4,11,16,44,64,121,176,256,484,704,1024,1331,1936,2816,4096,5324,
%T A107988 7744,11264,14641,16384,21296,30976,45056,58564,65536,85184,123904,
%U A107988 161051,180224,234256,262144,340736,495616,644204,720896,937024,1048576
%N A107988 Numbers of the form (4^i)*(11^j), with i, j >= 0.
%H A107988 Reinhard Zumkeller, <a href="/A107988/b107988.txt">Table of n, a(n) for n = 1..10000</a>
%F A107988 Sum_{n>=1} 1/a(n) = (4*11)/((4-1)*(11-1)) = 22/15. - _Amiram Eldar_, Sep 24 2020
%F A107988 a(n) ~ exp(sqrt(2*log(4)*log(11)*n)) / sqrt(44). - _Vaclav Kotesovec_, Sep 24 2020
%t A107988 n = 10^6; Flatten[Table[4^i*11^j, {i, 0, Log[4, n]}, {j, 0, Log[11, n/4^i]}]] // Sort (* _Amiram Eldar_, Sep 24 2020 *)
%o A107988 (Haskell)
%o A107988 import Data.Set (singleton, deleteFindMin, insert)
%o A107988 a107988 n = a107988_list !! (n-1)
%o A107988 a107988_list = f $ singleton (1,0,0) where
%o A107988    f s = y : f (insert (4 * y, i + 1, j) $ insert (11 * y, i, j + 1) s')
%o A107988          where ((y, i, j), s') = deleteFindMin s
%o A107988 -- _Reinhard Zumkeller_, May 15 2015
%Y A107988 Subsequence of A003596.
%Y A107988 Cf. A025617, A025618, A025619, A025620, A025621, A107462, A003597, A003598, A003599, A108090.
%K A107988 nonn
%O A107988 1,2
%A A107988 Douglas Winston (douglas.winston(AT)srupc.com), Jun 12 2005