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Search: id:A075577
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| A075577 |
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n^2 is a member if n^2 +(n-1)^2 and n^2 +(n+1)^2 are primes. |
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+0
1
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| 4, 25, 625, 900, 1225, 4900, 7225, 10000, 12100, 50625, 52900, 67600, 81225, 84100, 102400, 152100, 168100, 225625, 240100, 245025, 265225, 348100, 462400, 483025, 504100, 562500, 577600, 714025, 902500, 1166400, 1210000, 1288225, 1380625
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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a(2) onwards a(n)== 0 (mod 25).
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EXAMPLE
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900 is here because {m=30,b=m^2,a=(m-1)^2,c=(m+1)^2,q1=a+b,q2=b+c,PrimeQ[q1],PrimeQ[q2]}= {30, 900, 841, 961, 1741, 1861, True, True}
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MATHEMATICA
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Do[s=n^2+(n-1)^2; s1=n^2+(n+1)^2; If[PrimeQ[s]&&PrimeQ[s1], Print[n^2]], {n, 1, 5000}]
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CROSSREFS
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Adjacent sequences: A075574 A075575 A075576 this_sequence A075578 A075579 A075580
Sequence in context: A093959 A086216 A123129 this_sequence A004019 A072882 A014253
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 25 2002
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EXTENSIONS
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More terms from Labos E. (labos(AT)ana.sote.hu), Sep 27 2002
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