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A117329
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Determinants of 3 X 3 matrices of discrete blocks of 9 consecutive primes.
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1
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-78, 520, 480, -1548, -1920, -13668, 1408, -1316, -1252, 11760, 12264, 16992, 14520, 16220, -144, -87960, 31428, 35340, -1008, -1008, 240, 43464, -84768, 264, 431340, 45824, -28540, -29484, -56916, -672, 120960, -54260, 18164, 31528, -101736, -258264, 356448, 73440, 149552, -18616, 117864, 12620, 125280, 22064, -55428, 112272, -4992, -214536, -72184, 885960, 333720
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OFFSET
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1,1
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COMMENTS
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The number of negative values in this sequence appears to become smaller and smaller than the number of positive values. This suggests the ratios of these two numbers approach a limit as the number of terms increases. The smallest absolute value of the determinants in this sequence is 0. For example x=1009 in the PARI script will give a determinant of 0.
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LINKS
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FORMULA
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A 3 X 3 matrix with elements of first row a,b,c and second row d,e,f and third row g,h,i has a determinant D = aei+bfg+cdh-afh-bdi-ceg. Discrete prime blocks of 9 consecutive primes are substituted into a,b,c,d,e,f,g,h,i to evaluate D.
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EXAMPLE
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The first block of 9-primes is 2,3,5,7,11,13,17,19,23. So
D = 2*11*23+3*13*17+5*7*19-2*13*19-3*7*23-5*11*17 = -78, the first entry in the table.
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MATHEMATICA
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Table[Det[Partition[Prime[Range[9n+1, 9n+9]], 3]], {n, 0, 50}] (* Harvey P. Dale, Mar 24 2013 *)
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PROG
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(PARI) det3(n) = \ determinants of 3 X 3 discrete prime matrices { local(a, b, c, d, e, f, g, h, i, m=0, p=0, x, D); forstep(x=1, n, 9, a=prime(x); b=prime(x+1); c=prime(x+2); d=prime(x+3); e=prime(x+4); f=prime(x+5); g=prime(x+6); h=prime(x+7); i=prime(x+8); D = a*e*i+b*f*g+c*d*h-a*f*h-b*d*i-c*e*g; if(D<0, m++, p++); print1(D", "); ); print(); print("neg= "m); print("pos= "p); print("pos/neg = "p/m+.) }
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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