A098207 a(n) is the square of near-repdigit number A033175(n).

1, 961, 109561, 11095561, 1110955561, 111109555561, 11111095555561, 1111110955555561, 111111109555555561, 11111111095555555561, 1111111110955555555561, 111111111109555555555561

Offset: 0

Author

Labos Elemer, Oct 20 2004

Keywords

• nonn
• base
• easy

Comments

While repunit-squares are palindromic, squares of near repdigits provide other curious digit-patterns.

Links

• Index entries for linear recurrences with constant coefficients, signature (111, -1110, 1000).

Crossrefs

Cf. A033175, A055557.

Formula

a(n) = A033175(n)^2.

From Chai Wah Wu, Nov 09 2018: (Start)

a(n) = 111*a(n-1) - 1110*a(n-2) + 1000*a(n-3) for n > 2.

G.f.: (-4000*x^2 - 850*x - 1)/((x - 1)*(10*x - 1)*(100*x - 1)). (End)