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A073350 Primes not at the center of a 3 X 3 magic square of primes. 4
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 61, 67, 79, 83, 97, 101, 107, 113, 163, 181, 197, 199, 223, 229, 233, 277, 313, 317, 331, 433, 439, 457, 569, 859 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The "magic sum" is always thrice the central entry.

There are no other terms < 5000.

There are no other terms < 100000. - Robert Israel, Feb 16 2016

LINKS

Table of n, a(n) for n=1..40.

Index entries for sequences related to magic squares

MAPLE

N:= 10000: # to get all terms <= N

P:= select(isprime, {seq(p, p=3..2*N, 2)}):

count:= 1:

A[count]:= 2:

for ic from 1 while P[ic] <= N do

   c:= P[ic];

   V:= map(`-`, P[ic+1..-1], c) intersect map(t -> c-t, P[1..ic-1]);

   nv:= nops(V);

   VV:= {seq(seq(V[j]-V[i], j=i+1..nv), i=1..nv-1)} intersect V;

   nvv:= nops(VV);

   found:= false;

   for ia from 1 to nvv while not found do

     a:= VV[ia];

     for ib from ia+1 to nvv while VV[ib] < c - a do

       b:= VV[ib];

       if b <> 2*a and {c-a-b, c-a+b, c-b+a, c+a+b} subset P then

          found:= true;

          break

       fi

     od

   od:

   if not found then

     count:= count+1;

     A[count]:= c;

   fi

od:

seq(A[i], i=1..count); # Robert Israel, Feb 16 2016

CROSSREFS

Cf. A073473. A magic square with 59 at center is given in A024351.

Sequence in context: A118849 A049561 A080191 * A167773 A049545 A127566

Adjacent sequences:  A073347 A073348 A073349 * A073351 A073352 A073353

KEYWORD

nonn

AUTHOR

David W. Wilson, Aug 25 2002

STATUS

approved

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Last modified January 20 14:13 EST 2019. Contains 319333 sequences. (Running on oeis4.)