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

1, 961, 109561, 11095561, 1110955561, 111109555561, 11111095555561, 1111110955555561, 111111109555555561, 11111111095555555561, 1111111110955555555561, 111111111109555555555561, 11111111111095555555555561, 1111111111110955555555555561, 111111111111109555555555555561

Offset

0,2

Comments

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

Links

Andrew Howroyd, Table of n, a(n) for n = 0..100

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

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)

E.g.f.: exp(x)*(49 - 140*exp(9*x) + 100*exp(99*x))/9. - Elmo R. Oliveira, Nov 21 2025

Crossrefs

Cf. A033175, A055557.

Sequence in context: A274120 A063797 A231761 * A304315 A393861 A158414

Adjacent sequences: A098204 A098205 A098206 * A098208 A098209 A098210

Keyword

nonn,base,easy

Author

Labos Elemer, Oct 20 2004

Extensions

a(12) onward from Andrew Howroyd, Nov 08 2025

Status

approved