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 A004729 #26 Feb 16 2025 08:32:28 %S A004729 1,3,5,15,17,51,85,255,257,771,1285,3855,4369,13107,21845,65535,65537, %T A004729 196611,327685,983055,1114129,3342387,5570645,16711935,16843009, %U A004729 50529027,84215045,252645135,286331153,858993459,1431655765,4294967295 %N A004729 Divisors of 2^32 - 1 (for a(1) to a(31), the 31 regular polygons with an odd number of sides constructible with ruler and compass). %C A004729 The 32 divisors of the product of the 5 known Fermat primes. %C A004729 The only known odd numbers whose totient is a power of 2. - _Labos Elemer_, Dec 06 2000 %C A004729 Equals first 32 members of A001317. Also, equals first 32 members of A053576. - _Omar E. Pol_, Dec 10 2008 %C A004729 Omitting the first term a(0)=1 gives A045544 (the number of sides of constructible odd-sided regular polygons.) %D A004729 J. H. Conway and R. K. Guy, The Book of Numbers, Copernicus Press, New York, 1996; see p. 140. %H A004729 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RegularPolygon.html">Regular Polygon</a>, <a href="https://mathworld.wolfram.com/SierpinskiSieve.html">Sierpiński Sieve</a>, <a href="https://mathworld.wolfram.com/ConstructiblePolygon.html">Constructible Polygon</a> %H A004729 OEIS Wiki, <a href="/wiki/Constructible_odd-sided_polygons">Constructible odd-sided polygons</a> %H A004729 OEIS Wiki, <a href="/wiki/Sierpinski's_triangle">Sierpinski's triangle</a> %H A004729 <a href="/index/Di#divisors">Index entries for sequences related to divisors of numbers</a> %t A004729 Divisors[2^32-1] %o A004729 (PARI) divisors(1<<32-1) %Y A004729 Essentially same as A045544. %Y A004729 Cf. A000010, A000215, A001317, A003401, A003527, A004169, A004729, A019434, A045544, A047999, A053576, A054432. %K A004729 nonn,fini,full,easy %O A004729 0,2 %A A004729 _N. J. A. Sloane_ %E A004729 Edited by _Daniel Forgues_, Jun 17 2011