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%I #18 Mar 20 2019 19:11:32
%S 2,34,35,276,1520,2342,8882,32313,164065,265693,1123487,2421341,
%T 6250773,9995032,68353789,78927182
%N Least power of 3 having exactly n consecutive 9's in its decimal representation.
%C No more terms < 10^8. - _Bert Dobbelaere_, Mar 20 2019
%e a(3)=35 because 3^35 (i.e., 50031545098999707) is the smallest power of 3 to contain a run of 3 consecutive nines in its decimal form.
%t a = ""; Do[ a = StringJoin[a, "9"]; b = StringJoin[a, "9"]; k = 1; While[ StringPosition[ ToString[3^k], a] == {} || StringPosition[ ToString[3^k], b] != {}, k++ ]; Print[k], {n, 1, 10} ]
%o (Python)
%o def A131544(n):
%o ....m, s = 1, '9'*n
%o ....for i in range(1,10**9):
%o ........m *= 3
%o ........if s in str(m):
%o ............return i
%o ....return "search limit reached." # _Chai Wah Wu_, Dec 11 2014
%Y Cf. A195269, A131552, A131551, A131550, A131549, A131548, A131547, A131546, A131545.
%K more,nonn,base
%O 1,1
%A _Shyam Sunder Gupta_, Aug 26 2007
%E a(11)-a(14) from _Lars Blomberg_, Feb 02 2013
%E a(15) from _Bert Dobbelaere_, Mar 04 2019
%E a(16) from _Bert Dobbelaere_, Mar 20 2019
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