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A064013 Sum of first n^2 odd primes (=S) is divisible by n and S/n = n mod 2. 2
1, 35, 215, 225, 398, 2097, 5205, 7452, 22359, 98176, 169653 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

a(12) > 500000. - Donovan Johnson

LINKS

Table of n, a(n) for n=1..11.

EXAMPLE

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

PROG

(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, ))

CROSSREFS

Sequence in context: A232713 A007329 A101628 * A240137 A020262 A224104

Adjacent sequences:  A064010 A064011 A064012 * A064014 A064015 A064016

KEYWORD

nonn,hard

AUTHOR

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

EXTENSIONS

a(10)-a(11) from Donovan Johnson, Nov 30 2010

STATUS

approved

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Last modified December 9 10:23 EST 2016. Contains 278971 sequences.