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A070750
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sin(prime(n)*pi/2), where prime=A000040, pi=3.1415...
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17
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0, -1, 1, -1, -1, 1, 1, -1, -1, 1, -1, 1, 1, -1, -1, 1, -1, 1, -1, -1, 1, -1, -1, 1, 1, 1, -1, -1, 1, 1, -1, -1, 1, -1, 1, -1, 1, -1, -1, 1, -1, 1, -1, 1, 1, -1, -1, -1, -1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, 1, -1, 1, -1, 1, 1, -1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Also imaginary part of primes mapped as defined in A076340, A076341: a(n)=A076341(A000040(n)), real part = A076342.
Legendre symbol (-1/prime(n)) for n > 1. - T. D. Noe (noe(AT)sspectra.com), Nov 05 2003
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LINKS
| Eric Weisstein's World of Mathematics, Legendre Symbol
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FORMULA
| a(n) = 2 - prime(n) mod 4.
a(n) = (-1)^((prime(n)-1)/2) for n > 1 - T. D. Noe (noe(AT)sspectra.com), Nov 05 2003
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EXAMPLE
| p=4*k+1 (see A002144): a(p) = sin((4*k+1)*pi/2) = sin(2*k*pi+pi/2) = sin(pi/2) = 1; p=4*k+3 (see A002145): a(p) = sin((4*k+3)*pi/2) = sin(2*k*pi+3*pi/2) = sin(3*pi/2) = -1.
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PROG
| (PARI) apply(n->2-n%4), primes(100)) \\ Charles R Greathouse IV, Aug 21 2011
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CROSSREFS
| Cf. A070748, A070749, A002144, A002145.
Sequence in context: A011596 A011597 A070747 * A011598 A011599 A011600
Adjacent sequences: A070747 A070748 A070749 * A070751 A070752 A070753
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KEYWORD
| sign,nice
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 04 2002
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