A091686 a(n) = 0^n + ((n-9)/9)*(1-10^n).

1, 8, 77, 666, 5555, 44444, 333333, 2222222, 11111111, 0, -1111111111, -22222222222, -333333333333, -4444444444444, -55555555555555, -666666666666666, -7777777777777777, -88888888888888888, -999999999999999999, -11111111111111111110, -122222222222222222221

Offset

0,2

Links

Table of n, a(n) for n=0..20.

Index entries for linear recurrences with constant coefficients, signature (22,-141,220,-100).

Formula

a(n) = P(n, n+1, -10) where P(n, m, z) = Product_{k=0..n-1} (z - Sum_{j=1..m} w(n)^(j*k)), where w(n) = e^(2*Pi*i/n), i = sqrt(-1).

Prog

(PARI) a(n)=0^n+(n-9)/9*(1-10^n) \\ Charles R Greathouse IV, May 27 2026

Crossrefs

Sequence in context: A232087 A105429 A225348 * A091691 A024103 A187638

Adjacent sequences: A091683 A091684 A091685 * A091687 A091688 A091689

Keyword

sign,easy

Author

Paul Barry, Jan 29 2004

Status

approved