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 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). 14
 1, 3, 5, 15, 17, 51, 85, 255, 257, 771, 1285, 3855, 4369, 13107, 21845, 65535, 65537, 196611, 327685, 983055, 1114129, 3342387, 5570645, 16711935, 16843009, 50529027, 84215045, 252645135, 286331153, 858993459, 1431655765, 4294967295 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The 32 divisors of the product of the 5 known Fermat primes. The only known odd numbers whose totient is a power of 2. - Labos Elemer, Dec 06 2000 Equals first 32 members of A001317. Also, equals first 32 members of A053576. - Omar E. Pol, Dec 10 2008 Omitting the first term a(0)=1 gives A045544 (the number of sides of constructible odd-sided regular polygons.) REFERENCES J. H. Conway and R. K. Guy, The Book of Numbers, Copernicus Press, New York, 1996; see p. 140. LINKS Eric Weisstein's World of Mathematics, Regular Polygon, Sierpiński Sieve, Constructible Polygon OEIS Wiki, Constructible odd-sided polygons OEIS Wiki, Sierpinski's triangle MATHEMATICA Divisors[2^32-1] PROG (PARI) divisors(1<<32-1) CROSSREFS Essentially same as A045544. Cf. A000010, A000215, A001317, A003401, A003527, A004169, A004729, A019434, A045544, A047999, A053576, A054432. Sequence in context: A094358 A003527 * A045544 A001317 A053576 A197818 Adjacent sequences:  A004726 A004727 A004728 * A004730 A004731 A004732 KEYWORD nonn,fini,full,easy AUTHOR EXTENSIONS Edited by Daniel Forgues, Jun 17 2011 STATUS approved

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