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A139514
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Denominators of an Egyptian fraction for Pi, using only prime numbers and allowing repetitions.
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9
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2, 2, 2, 2, 2, 2, 11, 23, 139, 90439, 33156439637, 87550414616253068989, 751473085670398285260591818545427587609, 9405222481347574254746223047204588161218024092399608112777273401749812628709
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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EXAMPLE
| 1/2+1/2+1/2+1/2+1/2+1/2 = 3 (integer part of Pi)
3+1/11+1/23+1/139+1/90439 gives an approximation which is good to 10 decimal digits.
Adding the other fractions we reach a good approximation to 19, 38, 75, 149, 296, 591 decimal digits.
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MAPLE
| P:=proc(n) local a, i; a:=evalf(Pi-3, 100); for i from 1 by 1 to 6 do print(2); od; for i from 1 by 1 to n do if 1/ithprime(i)<a then a:=a-1/ithprime(i); print(a); print(ithprime(i)); fi; od; end: P(100000);
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CROSSREFS
| Cf. A139515-A139523.
Sequence in context: A172009 A202448 A129381 * A190617 A068323 A054990
Adjacent sequences: A139511 A139512 A139513 * A139515 A139516 A139517
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KEYWORD
| easy,nonn
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AUTHOR
| Paolo P. Lava & Giorgio Balzarotti (paoloplava(AT)gmail.com), Apr 24 2008
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