A211396 Smallest prime substring of n, or 0 if no such substring exists.

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

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

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: A331045 A331044 A093438 * A331097 A047814 A365276

Adjacent sequences: A211393 A211394 A211395 * A211397 A211398 A211399

Keyword

nonn,base,look

Author

Reinhard Zumkeller, Feb 08 2013

Status

approved