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 A171493 #8 Mar 25 2025 23:19:11 %S A171493 1,7,45,55,67,100,433,4950,5050,38212,65068,190576,295075,299035, %T A171493 310024,336700,343333,394615,414558,433566,448228,450550,467236, %U A171493 475497,476191,486486,499500,500500,523513,534898,549550,599743,622414,628408,647362 %N A171493 "Kaprekar quadruples": digits of X^4 taken D at a time sum to X (where D is number of digits in X.) %C A171493 Referred to as "natural" Kaprekar numbers on Munafo webpage because a(n) and the 4 pieces of a(n)^4 must all have the same number of digits (some of which can be leading zeros). Analogous to A053816 for squares, as opposed to A006886 and A045913 which allow irregular divisions. %H A171493 Robert Gerbicz, <a href="/A171493/b171493.txt">Table of n, a(n) for n = 1..10852</a> %H A171493 Shyam Sunder Gupta, <a href="https://doi.org/10.1007/978-981-97-2465-9_9">On Some Marvellous Numbers of Kaprekar</a>, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 9, 275-315. %H A171493 R. Munafo, <a href="http://www.mrob.com/pub/math/seq-kaprekar.html">Kaprekar Sequences</a> %e A171493 7^4 = 2401 ; 2+4+0+1 = 7. 67^4 = 20151121 ; 20+15+11+21 = 67. 4950^4 = 600372506250000 ; 0600+3725+0625+0000 = 4950. %Y A171493 Cf. A006886, A006887, A045913, A053816 %K A171493 base,nonn %O A171493 1,2 %A A171493 _Robert Munafo_, Dec 10 2009 %E A171493 Added term a(1)=1, _Robert Gerbicz_, Jul 28 2011