This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A102831 #18 Feb 16 2025 08:32:56
%S A102831 2,2,2,4,8,14,25,43,78,139,246,437,779,1384,2461,4376,7783,13840,
%T A102831 24612,43765,77828,138400,246114,437658,778280,1383998,2461136,
%U A102831 4376586,7782795,13839982,24611356,43765867,77827942,138399825,246113559
%N A102831 Number of n-digit 4th powers.
%C A102831 The number 0 is considered a 1-digit 4th power. This is consistent with A062941 which considers 0 a 1-digit cube, but is inconsistent with A049415 which does not consider 0 a 1-digit square.
%H A102831 Alois P. Heinz, <a href="/A102831/b102831.txt">Table of n, a(n) for n = 1..1000</a>
%H A102831 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/BiquadraticNumber.html">Biquadratic Number</a>.
%e A102831 a(1)=2 because there are 2 1-digit 4th powers, 0 and 1.
%p A102831 r:= proc(n, k) local b; b:= iroot(n, k); b+`if`(b^k<n, 1, 0) end:
%p A102831 a:= n-> r(10^n, 4) -r(10^(n-1), 4) +`if`(n=1, 1, 0):
%p A102831 seq(a(n), n=1..50); # _Alois P. Heinz_, Sep 12 2012
%t A102831 f[n_] := If[n == 1, 2, Ceiling[ Sqrt[ Sqrt[10^n]]] - Ceiling[ Sqrt[ Sqrt[10^(n - 1)]]]]; Table[ f[n], {n, 34}] (* _Robert G. Wilson v_, Mar 03 2005 *)
%Y A102831 Cf. A062941, A049415.
%Y A102831 Column k=4 of A216653.
%K A102831 easy,nonn,base
%O A102831 1,1
%A A102831 _James R. Buddenhagen_, Feb 27 2005
%E A102831 More terms from _Robert G. Wilson v_, Mar 03 2005