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A053380 a(n) contains n digits (either '8' or '9') and is divisible by 2^n. 2

%I #5 Jun 13 2020 15:19:05

%S 8,88,888,9888,89888,989888,9989888,89989888,989989888,8989989888,

%T 98989989888,898989989888,8898989989888,98898989989888,

%U 998898989989888,8998898989989888,98998898989989888,898998898989989888

%N a(n) contains n digits (either '8' or '9') and is divisible by 2^n.

%H Ray Chandler, <a href="/A053380/b053380.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n)=a(n-1)+10^(n-1)*(8+[a(n-1)/2^(n-1) mod 2]) i.e. a(n) ends with a(n-1); if (n-1)-th term is divisible by 2^n then n-th term begins with an 8, if not then n-th term begins with a 9.

%Y Cf. A023415, A050621, A050622, A035014.

%K base,nonn

%O 1,1

%A _Henry Bottomley_, Mar 06 2000

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Last modified March 29 00:26 EDT 2024. Contains 371264 sequences. (Running on oeis4.)