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A211396
Smallest prime substring of n, or 0 if no such substring exists.
2
0, 0, 2, 3, 0, 5, 0, 7, 0, 0, 0, 11, 2, 3, 0, 5, 0, 7, 0, 19, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 0, 41, 2, 3, 0, 5, 0, 7, 0, 0, 5, 5, 2, 3, 5, 5, 5, 5, 5, 5, 0, 61, 2, 3, 0, 5, 0, 7, 0, 0, 7, 7, 2, 3, 7, 5, 7, 7, 7, 7, 0, 0, 2, 3, 0, 5
OFFSET
0,3
COMMENTS
a(n) <= A047814(n);
a(n) = 0 iff A039997(n) = 0, cf. A062115;
a(n) = n iff n is prime and A039997(n) = 1.
LINKS
PROG
(Haskell)
import Data.List (isInfixOf)
a211396 n = if null ips then 0 else head ips
where ips = [p | p <- takeWhile (<= n) a000040_list,
show p `isInfixOf` show n]
CROSSREFS
Sequence in context: A377777 A093438 A375548 * A331097 A047814 A365276
KEYWORD
nonn,base,look
AUTHOR
Reinhard Zumkeller, Feb 08 2013
STATUS
approved