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A018142 Powers of fifth root of 10 rounded to nearest integer.

%I A018142 #23 Jan 29 2025 17:47:23
%S A018142 1,2,3,4,6,10,16,25,40,63,100,158,251,398,631,1000,1585,2512,3981,
%T A018142 6310,10000,15849,25119,39811,63096,100000,158489,251189,398107,
%U A018142 630957,1000000,1584893,2511886,3981072,6309573
%N A018142 Powers of fifth root of 10 rounded to nearest integer.
%H A018142 Chai Wah Wu, <a href="/A018142/b018142.txt">Table of n, a(n) for n = 0..1000</a>
%F A018142 a(n) = round(10^(n/5)). - _Wesley Ivan Hurt_, Jun 23 2015
%p A018142 A018142:=n->round(10^(n/5)): seq(A018142(n), n=0..50); # _Wesley Ivan Hurt_, Jun 23 2015
%t A018142 Round[(10^(Range[0, 50]/5))] (* _Paolo Xausa_, Jul 02 2024 *)
%t A018142 Round[Surd[10,5]^Range[0,50]] (* _Harvey P. Dale_, Jan 29 2025 *)
%o A018142 (Python)
%o A018142 from gmpy2 import iroot_rem
%o A018142 def A018142(n):
%o A018142     i,j = iroot_rem(10**n,5)
%o A018142     return int(i) + int(32*j >= 10*i*(4*i*(2*i*(i + 1) + 1) + 1) + 1) # _Chai Wah Wu_, Aug 18 2016
%Y A018142 Cf. A011095.
%K A018142 nonn,easy
%O A018142 0,2
%A A018142 _N. J. A. Sloane_