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%I #6 May 06 2022 13:13:51
%S 8,6,4,7,2,9,9,2,6,1,9,7,3,3,6,9,7,0,2,9,9,9,9,3,8,3,7,5,9,9,8,9,7,3,
%T 4,4,9,9,7,0,0,2,9,9,9,9,9,9,3,9,4,8,2,6,4,9,9,9,6,1,9,4,6,7,2,1,9,9,
%U 9,7,0,0,0,2,9,9,9,9,9,9,9,9,5
%N Constant whose decimal expansion is the concatenation of the largest n-digit cube A061435(n), for n = 1, 2, 3, ...
%C The terms of sequence A340115 converge to this sequence of digits, and to this constant, up to powers of 10.
%F c = 0.86472992619733697029999383759989734499700299999939482649996194672...
%F = Sum_{k >= 1} 10^(-k(k+1)/2)*floor(10^(k/3)-1)^3
%F a(-n(n+1)/2) = 9 for all n >= 3;
%e The largest cube with 1, 2, 3, 4, ... digits is, respectively, 8 = 2^3, 64 = 4^3, 729 = 9^3, 9261 = 21^3, ..., cf. A061435.
%e Here we list the sequence of digits of these numbers: 8; 6, 4; 7, 2, 9; 9, 2, 6, 1; ...
%e This can be considered, as for the Champernowne and Copeland-Erdős constants, as the decimal expansion of a real constant 0.864729926...
%o (PARI) concat([digits(sqrtnint(10^k-1,3)^3)|k<-[1..14]]) \\ as seq. of digits
%o c(N=20)=sum(k=1,N,.1^(k*(k+1)/2)*sqrtnint(10^k-1,3)^3) \\ as constant
%Y Cf. A061435 (largest n-digit cube), A340115 (has this as "limit"), A340208 (similar, with smallest n-digit cubes, limit of A215692), A340207 (same for squares, limit of A339978), A340220 (same for primes), A340222 (same for semiprimes), A340219 (similar, with smallest primes, limit of A215641), A340221 (similar, with smallest semiprimes, limit of A215647).
%Y Cf. A033307 (Champernowne constant), A030190 (binary), A001191 (concatenation of all squares), A134724 (cubes), A033308 (primes: Copeland-Erdős constant).
%K nonn,base,cons
%O 0,1
%A _M. F. Hasler_, Jan 01 2021
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