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A113213
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Smallest number m such that 2^n +/- m are primes.
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1
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0, 1, 3, 3, 9, 3, 21, 15, 9, 15, 21, 3, 45, 135, 75, 15, 99, 93, 99, 315, 105, 105, 15, 75, 339, 117, 261, 183, 351, 453, 1281, 267, 675, 867, 819, 117, 69, 2343, 1995, 1005, 2949, 165, 741, 603, 315, 1287, 1629, 243, 519, 765, 165, 1233, 741, 1797, 339, 177
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| At n>=3 all terms are multiples of 3.
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EXAMPLE
| a(1)=0 because 2^1 +/- 0 are primes; a(2)=1 because 2^2 -/+ 1 are primes;
a(33)=675 because 2^33 +/- 675 are closest (to each other) primes.
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MATHEMATICA
| f[n_]:=Module[{a=2^n, i=1}, While[!PrimeQ[a+i]||!PrimeQ[a-i], i++]; i]; Join[{0}, Rest[Array[f, 80]]] (* From Harvey P. Dale, Apr 25 2011 *)
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CROSSREFS
| Sequence in context: A166466 A068219 A157031 * A088032 A066572 A104195
Adjacent sequences: A113210 A113211 A113212 * A113214 A113215 A113216
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KEYWORD
| nonn
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AUTHOR
| Zak Seidov (zakseidov(AT)yahoo.com), Jan 07 2006
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