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A086564
Smallest k such that 10^k + 1 has n distinct prime divisors.
0
0, 4, 3, 11, 9, 36, 15, 33, 39, 69, 63, 45, 171, 117, 243, 105, 150, 135, 165, 255, 231, 210
OFFSET
1,2
COMMENTS
a(27) = 330; a(28) = 315; a(23) >= 347. - Max Alekseyev, Jun 18 2023
a(23) <= 385. - Jon E. Schoenfield, Jun 18 2023
FORMULA
a(n) = log_10(A086563(n) - 1).
EXAMPLE
a(5) = 9 = log_10(1000000001 - 1).
MATHEMATICA
Module[{nn=70, pn}, pn=PrimeNu/@(10^Range[0, nn]+1); Flatten[Table[Position[pn, n, 1, 1], {n, 12}]]]-1 (* Harvey P. Dale, Jun 10 2023 *)
CROSSREFS
Smallest inverse of A119704.
Cf. A086563.
Sequence in context: A370630 A005013 A241643 * A316966 A295727 A200073
KEYWORD
more,nonn
AUTHOR
Amarnath Murthy, Aug 31 2003
EXTENSIONS
More terms from Sascha Kurz, Sep 22 2003
a(10)-a(12) from David Wasserman, Mar 28 2005
a(13)-a(22) from Max Alekseyev, Apr 27 2010
STATUS
approved