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%I #12 Mar 22 2020 17:30:27
%S 91,990,199396,998991,399949903,2919969990,39999939903,999999911791,
%T 9999192996990,499798990999990,99597939989199996,999699998689998991,
%U 19699899919999499091,999532899999499099996,999999859999976929990,199793999409939999989991,138999999499599999199995,99996999694999999299662991
%N Smallest triangular number containing exactly n 9's.
%t nsmall = Table[Infinity, 20];
%t For[i = 0, i <= 10^6, i++, p = PolygonalNumber[i];
%t n0 = Count[IntegerDigits[p], 9];
%t If[nsmall[[n0]] > p, nsmall[[n0]] = p]];
%t ReplaceAll[nsmall, Infinity -> "?"] (* _Robert Price_, Mar 22 2020 *)
%Y Cf. A048364, A036517-A036525.
%K nonn,base
%O 1,1
%A _David W. Wilson_
%E a(12)-a(18) from _Giovanni Resta_, Oct 30 2019
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