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A145781
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Least m >= 0 which when added to primorial(n) yields a square.
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3
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2, 3, 6, 15, 91, 246, 715, 3535, 21099, 95995, 175470, 4468006, 31516774, 192339970, 212951314, 5138843466, 76699112491, 103728576730, 3051100701874, 14417674958635, 245230361204214, 2296196521511806, 10940476546738414
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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a(1)= 4 - 2 = 2, a(2)= 9 - 2*3 = 3, a(3)= 36 - 2*3*5 = 6, a(4)= 225 - 2*3*5*7 = 15, and a(5)= 2401 - 2*3*5*7*11 = 91.
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MATHEMATICA
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(IntegerPart[Sqrt[#]]+1)^2-#&/@Rest[FoldList[Times, 1, Prime[Range[30]]]] (* Harvey P. Dale, Jan 14 2011 *)
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PROG
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(PARI) j=[]; for (n=1, 30, j=concat(j, (ceil(sqrt(prod(i=1, n, prime(i))))^2 -prod(i=1, n, prime(i))))); j
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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