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a(n)^3 is smallest cube containing exactly n 0's.
20

%I #21 Nov 21 2018 00:35:25

%S 1,0,52,10,160,520,100,1600,5200,1000,16000,52000,10000,160000,520000,

%T 100000,1600000,5200000,1000000,16000000,52000000,10000000,160000000,

%U 520000000,100000000,1600000000,5200000000,1000000000

%N a(n)^3 is smallest cube containing exactly n 0's.

%C a(n) is the index of the first occurrence of n in A269250.-- Is there an index n = 3k+1 or n = 3k+2 from which on the pattern a(3k+1) = 16*10^k resp. a(3k+2) = 52*10^k is no longer true? - _M. F. Hasler_, Feb 20 2016

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CubicNumber.html">Cubic Number</a>

%F a(3k) = 10^k; a(3k+1) <= 16*10^k (k>0), a(3k+2) <= 52*10^k. - _M. F. Hasler_, Feb 20 2016

%t nsmall = Table[Infinity, 12];

%t For[i = 0, i <= 52000, i++, n0 = Count[IntegerDigits[i^3], 0];

%t If[nsmall[[n0]] > i, nsmall[[ n0]] = i]];

%t Join[{1}, nsmall] (* _Robert Price_, Sep 26 2018 *)

%Y Cf. A036527, A269250.

%K nonn,base,more

%O 0,3

%A _Patrick De Geest_, Mar 15 1999

%E a(19)-a(27) from _Lars Blomberg_, Jun 12 2011