|
%I #28 Jan 18 2024 09:33:50
%S 1,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
%T 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
%U 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9
%N 1 followed by infinitely many 9's.
%C The digital root of 9^(n-1). - _Cino Hilliard_, Dec 31 2004
%C With interpolated zeros (1,0,9,0,9,0,9,0,...) this is the number of hours between times when the hands of a two-handed clock cross. - _Halfdan Skjerning_, Aug 18 2017
%H Brady Haran and Cliff Stoll, <a href="https://www.youtube.com/watch?v=HcqdqsQq-6M">When do clock hands overlap?</a>, Numberphile video (2017)
%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (1).
%F G.f.: x*(1 + 8*x)/(1 - x). - _Chai Wah Wu_, Aug 19 2017
%F E.g.f.: 9*(exp(x) - 1) - 8*x. - _Stefano Spezia_, Oct 16 2023
%t PadRight[{1},100,9] (* _Paolo Xausa_, Oct 16 2023 *)
%Y Cf. A178181, A010734, A180599, A100403, A100401.
%K nonn,easy
%O 1,2
%A _N. J. A. Sloane_, Aug 19 2017
|
