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A064013
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Sum of first n^2 odd primes (=S) is divisible by n and S/n = n mod 2.
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2
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1, 35, 215, 225, 398, 2097, 5205, 7452, 22359, 98176, 169653
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OFFSET
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1,2
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COMMENTS
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A necessary condition for the existence of a magic square consisting of the first n^2 odd primes.
a(12) > 500000. - Donovan Johnson
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LINKS
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Table of n, a(n) for n=1..11.
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EXAMPLE
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a(2)=35 since 3+5+ ... +9941 = 5706505 = 35*163043 and 163043 = 35 mod 2.
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PROG
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(PARI) s=0; t=0; u=1; forprime(x=3, 2500000, s=s+x; t=t+1; if(t==u*u, if(s%u==0&(s\u)%2==u%2, print(u), ); u=u+1, ))
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CROSSREFS
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Sequence in context: A219942 A007329 A101628 * A020262 A224104 A195968
Adjacent sequences: A064010 A064011 A064012 * A064014 A064015 A064016
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KEYWORD
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nonn,hard
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AUTHOR
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H. K. Gottlob Maier (1korrago(AT)freenet.de), Sep 07, 2001
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EXTENSIONS
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a(10)-a(11) from Donovan Johnson, Nov 30 2010
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STATUS
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approved
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