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A073019
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Numbers n such that the absolute value of the real part of (1+2*I)^n is prime.
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0
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2, 3, 4, 5, 7, 11, 13, 17, 19, 89, 163, 167, 233, 251, 349, 401, 757, 1423, 3049, 3643, 11987
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..21.
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FORMULA
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{n: |A006495(n)| in A000040}.
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MAPLE
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A006495 := proc(n) add((-4)^l*binomial(n, 2*l), l=0..floor(n/2)) ; end proc:
isA073019 := proc(n) isprime(abs(A006495(n))) ; end proc:
for n from 1 do if isA073019(n) then print(n) ; end if; end do: # R. J. Mathar, Sep 06 2011
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MATHEMATICA
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x=1; For[n=1, n<=14000, n++, {x=(1+2*I)*x, If[PrimeQ[Re[x]], Print[n]]}]
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CROSSREFS
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Cf. A006495.
Sequence in context: A211781 A046022 A175787 * A174291 A007885 A192586
Adjacent sequences: A073016 A073017 A073018 * A073020 A073021 A073022
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre, Aug 03 2002
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EXTENSIONS
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Edited by John W. Layman, Aug 13 2002
a(21) from Robert G. Wilson v, Aug 22 2002
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STATUS
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approved
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