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A064013 Sum of first n^2 odd primes (=S) is divisible by n and S/n = n mod 2. 2

%I

%S 1,35,215,225,398,2097,5205,7452,22359,98176,169653

%N Sum of first n^2 odd primes (=S) is divisible by n and S/n = n mod 2.

%C A necessary condition for the existence of a magic square consisting of the first n^2 odd primes.

%C a(12) > 500000. - Donovan Johnson

%e a(2)=35 since 3+5+ ... +9941 = 5706505 = 35*163043 and 163043 = 35 mod 2.

%o (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,))

%K nonn,hard

%O 1,2

%A H. K. Gottlob Maier (1korrago(AT)freenet.de), Sep 07, 2001

%E a(10)-a(11) from _Donovan Johnson_, Nov 30 2010

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Last modified September 21 22:07 EDT 2019. Contains 327283 sequences. (Running on oeis4.)