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 A284602 #29 Nov 19 2023 21:17:11 %S A284602 1,2,4,5,7,8,10,11,13,14,16,17,19,20,21,22,23,25,26,28,29,32,33,34,35, %T A284602 38,39,40,42,44,46,47,49,50,51,52,55,56,57,58,59,61,63,64,65,66,68,69, %U A284602 70,73,76,77,78,80,84,85,87,88,89,91,92,94,95,97,98,99,100,101,102,103,104,105,109,110,112,113,114,115 %N A284602 Numbers k such that the decimal representation of 1/k is either finite or has even period. %C A284602 All numbers of the form 2^i*5^j with i, j >= 0 are in this sequence (numbers with a finite decimal expansion). %C A284602 From _Robert G. Wilson v_, Apr 02 2017: (Start) %C A284602 If k is in the sequence, then so are 2k and 5k. %C A284602 The complement of A284601. %C A284602 Primitives: 1, 7, 11, 13, 17, 19, 21, 23, 29, 33, 39, 47, 49, 51, 57, 59, 61, 63, ..., . %C A284602 (End) %H A284602 Robert G. Wilson v, <a href="/A284602/b284602.txt">Table of n, a(n) for n = 1..10000</a> %H A284602 <a href="/index/1#1overn">Index entries for sequences related to decimal expansion of 1/n</a> %e A284602 14 is in the sequence because 1/14 = 0.0714285(714285)..., whose period is 6, an even number. %t A284602 Select[Range[115], Mod[Length[RealDigits[1/#][[1, -1]]], 2] == 0 & ] %Y A284602 Cf. A002371, A003592, A028416, A051626, A206586, A284601. %K A284602 nonn,base %O A284602 1,2 %A A284602 _Ilya Gutkovskiy_, Mar 30 2017