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A117767
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a(n) is the differences between the smallest square greater than prime(n) and the largest square less than prime(n), where prime(n) = A000040(n) is the n-th prime number.
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0
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3, 3, 5, 5, 7, 7, 9, 9, 9, 11, 11, 13, 13, 13, 13, 15, 15, 15, 17, 17, 17, 17, 19, 19, 19, 21, 21, 21, 21, 21, 23, 23, 23, 23, 25, 25, 25, 25, 25, 27, 27, 27, 27, 27, 29, 29, 29, 29, 31, 31, 31, 31, 31, 31, 33, 33, 33, 33, 33, 33, 33, 35, 35, 35, 35, 35, 37, 37, 37, 37, 37, 37
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| a(n) = 2*floor(sqrt(prime(n)))+1 - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 21 2006
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EXAMPLE
| The 7-th prime number is 17, which is between the consecutive squares 16 and 25, so a(7) = 25-16 = 9.
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MATHEMATICA
| a[n_]:=2Floor[Sqrt[Prime[n]]]+1
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PROG
| (PARI) { forprime(p=2, 200, f = floor(sqrt(p)) ; print1(2*f+1, ", ") ; ) ; } - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 21 2006
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CROSSREFS
| Cf. A000040.
Cf. a(n) = 2*A000006(n) + 1.
Sequence in context: A129337 A133909 A177691 * A063196 A127630 A109613
Adjacent sequences: A117764 A117765 A117766 * A117768 A117769 A117770
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KEYWORD
| easy,nonn
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AUTHOR
| Odimar Fabeny (aifab(AT)yahoo.com.br), Apr 15 2006
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EXTENSIONS
| More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 21 2006
Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Jun 03 2006
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