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A004729
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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).
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12
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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; internal format)
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OFFSET
| 0,2
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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 E. (labos(AT)ana.sote.hu), Dec 06 2000
Equals first 32 members of A001317. Also, equals first 32 members of A053576. [From Omar E. Pol (info(AT)polprimos.com), Dec 10 2008]
Omitting the first term a(0)=1 gives A045544 (the number of sides of constructible odd-sided regular polygons.)
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REFERENCES
| J. H. Conway and R. K. Guy, The Book of Numbers, Copernicus Press, New York, 1996; see p. 140.
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LINKS
| Index entries for sequences related to divisors of numbers
Eric Weisstein's World of Mathematics, Regular Polygon, Sierpinski Sieve, Constructible Polygon
OEIS Wiki, Constructible odd-sided polygons
OEIS Wiki, Sierpinski's triangle
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MATHEMATICA
| Divisors[2^32-1]
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PROG
| (PARI) divisors(1<<32-1)
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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 A077406
Adjacent sequences: A004726 A004727 A004728 * A004730 A004731 A004732
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KEYWORD
| nonn,fini,full,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| Edited by Daniel Forgues (kephalopod(AT)gmail.com), Jun 17 2011
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