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A098210
a(n) = -1 + A093137(n)^2.
4
0, 15, 1155, 111555, 11115555, 1111155555, 111111555555, 11111115555555, 1111111155555555, 111111111555555555, 11111111115555555555, 1111111111155555555555, 111111111111555555555555
OFFSET
0,2
LINKS
FORMULA
a(n) = (1/9)*(10^n-1)*(5+10^n). - Vincenzo Librandi, Jun 02 2013
EXAMPLE
Like other -1 + square of near-repdigits give special digit patterns: (33333334^2) - 1 = 11111115555555.
MATHEMATICA
Table[(1/9) (10^n - 1) (5 + 10^n), {n, 0, 25}] (* Vincenzo Librandi, Jun 02 2013 *)
PROG
(Magma) [(1/9)*(10^n-1)*(5+10^n): n in [0..15]]; // Vincenzo Librandi, Jun 02 2013
CROSSREFS
Cf. A093137.
Sequence in context: A212857 A266581 A337677 * A090213 A230669 A027492
KEYWORD
nonn,easy
AUTHOR
Labos Elemer, Oct 20 2004
STATUS
approved