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A208241
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Smallest prime greater than n, with n as prefix in binary representation.
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8
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2, 5, 7, 17, 11, 13, 29, 17, 19, 41, 23, 97, 53, 29, 31, 67, 71, 37, 79, 41, 43, 89, 47, 97, 101, 53, 109, 113, 59, 61, 127, 131, 67, 137, 71, 73, 149, 307, 79, 163, 83, 337, 173, 89, 181, 373, 191, 97, 197, 101, 103, 211, 107, 109, 223, 113, 229, 233, 239
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listen;
history;
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internal format)
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OFFSET
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1,1
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COMMENTS
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LINKS
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MAPLE
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local nbin, len, suf, sufbin, pbin, p ;
nbin := convert(n, base, 2) ;
for len from 1 do
for suf from 0 to 2^len-1 do
sufbin := convert(suf, base, 2) ;
while nops(sufbin) < len do
sufbin := [op(sufbin), 0] ;
end do:
pbin := [op(sufbin), op(nbin)] ;
p := add( 2^(i-1)*op(i, pbin), i=1..nops(pbin) ) ;
if isprime(p) then
return p ;
end if;
end do:
end do:
end proc:
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PROG
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(Haskell)
import Data.List (genericIndex, find, isPrefixOf)
import Data.Maybe (fromJust)
a208241 = genericIndex a208241_list
a208241_list = f nns $ filter ((== 1) . a010051' . fst) nns where
f mms'@((m, ms):mms) pps'@((p, ps):pps) =
if m == p then f mms' pps else q : f mms pps'
where q = fst $ fromJust $ find ((ms `isPrefixOf`) . snd) pps'
nns = zip [1..] $ map reverse $ tail a030308_tabf
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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