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A053376 a(n) contains n digits (either '1' or '8') and is divisible by 2^n. 1
8, 88, 888, 1888, 81888, 181888, 8181888, 18181888, 118181888, 8118181888, 88118181888, 888118181888, 8888118181888, 88888118181888, 888888118181888, 1888888118181888, 81888888118181888, 181888888118181888 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..18.

FORMULA

a(n)=a(n-1)+10^(n-1)*(8-7*[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 1.

MATHEMATICA

Table[Select[FromDigits/@Tuples[{1, 8}, n], Divisible[#, 2^n]&], {n, 20}]// Flatten (* Harvey P. Dale, Aug 20 2017 *)

CROSSREFS

Cf. A023411, A050621, A050622, A035014.

Sequence in context: A271939 A043043 A003492 * A053377 A053378 A062185

Adjacent sequences:  A053373 A053374 A053375 * A053377 A053378 A053379

KEYWORD

base,nonn

AUTHOR

Henry Bottomley, Mar 06 2000

STATUS

approved

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Last modified May 31 13:01 EDT 2020. Contains 334748 sequences. (Running on oeis4.)