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A319880
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Difference between 2^n and the product of primes less than or equal to n.
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0
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0, 1, 2, 2, 10, 2, 34, -82, 46, 302, 814, -262, 1786, -21838, -13646, 2738, 35506, -379438, -248366, -9175402, -8651114, -7602538, -5505386, -214704262, -206315654, -189538438, -155984006, -88875142, 45342586, -5932822318, -5395951406, -198413006482
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OFFSET
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0,3
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COMMENTS
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This sequence shows 2^n is neither a lower bound nor an upper bound for the primorials.
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LINKS
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FORMULA
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a(n) = 2^n - n#, where n# is the product of primes less than or equal to n (A034386).
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MAPLE
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restart;
with(NumberTheory);
a := n -> 2^n-product(ithprime(i), i = 1 .. PrimeCounting(n)):
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MATHEMATICA
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Table[2^n - Times@@Select[Range[n], PrimeQ], {n, 0, 31}]
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PROG
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(PARI) a(n) = 2^n - prod(k=1, primepi(n), prime(k)); \\ Michel Marcus, Nov 05 2018
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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