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A145781
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Terms of this sequence are integers which need to be added to the product of successive primes to make the nearest perfect square.
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0
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| 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 a(5)= 2401 - 2*3*5*7*11 = 91
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MATHEMATICA
| (IntegerPart[Sqrt[#]]+1)^2-#&/@Rest[FoldList[Times, 1, Prime[Range[30]]]] [From Harvey P. Dale, Jan. 14, 2011]
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PROG
| (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
| Sequence in context: A116632 A007364 A014627 * A109162 A028688 A030753
Adjacent sequences: A145778 A145779 A145780 * A145782 A145783 A145784
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KEYWORD
| nonn
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AUTHOR
| Alexander R. Povolotsky (pevnev(AT)juno.com), Oct 18 2008
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