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A088115 a(n) = largest prime using least number of possible digits with a digit sum n, or 0 if no such number exists. E.g., if n > 9 and there are no two-digit primes with a given digit sum n then three-digit numbers are explored and so on. 0
0, 2, 3, 31, 5, 0, 7, 71, 0, 73, 83, 0, 67, 59, 0, 97, 89, 0, 991, 983, 0, 967, 977, 0, 997, 9791, 0, 9973, 9929, 0, 9967, 9887, 0, 99961, 8999, 0, 99991, 99929, 0, 99877, 99689, 0, 98899, 99989, 0, 999883, 999983, 0, 999769, 999959, 0, 999979, 989999, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
a(26) = 9719 as both 989 and 899 are composite. This is the first genuine case in which the number of digits used is more than floor(n/9) + 1 (after single-digit composite even numbers 4 and 8).
LINKS
EXAMPLE
a(7) = 7.
a(8) = 71 as 8 is not a prime.
CROSSREFS
Sequence in context: A326224 A270483 A217370 * A230627 A048986 A093712
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Sep 25 2003
EXTENSIONS
More terms from David Wasserman, Jul 25 2005
STATUS
approved

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Last modified July 22 13:50 EDT 2024. Contains 374499 sequences. (Running on oeis4.)