A098210 a(n) = -1 + A093137(n)^2.

0, 15, 1155, 111555, 11115555, 1111155555, 111111555555, 11111115555555, 1111111155555555, 111111111555555555, 11111111115555555555, 1111111111155555555555, 111111111111555555555555

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..100

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

Adjacent sequences: A098207 A098208 A098209 * A098211 A098212 A098213

Keyword

nonn,easy

Author

Labos Elemer, Oct 20 2004

Status

approved