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A061285 a(n) = 2^((prime(n) - 1)/2). 3
2, 4, 8, 32, 64, 256, 512, 2048, 16384, 32768, 262144, 1048576, 2097152, 8388608, 67108864, 536870912, 1073741824, 8589934592, 34359738368, 68719476736, 549755813888, 2199023255552, 17592186044416, 281474976710656, 1125899906842624, 2251799813685248 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
COMMENTS
Square root of 2^(prime(n) - 1), i.e., the smallest number that has prime(n) divisors.
LINKS
FORMULA
a(n) = sqrt(min(x; A000005(x) = prime(n))) = sqrt(A034785(n)/2) = sqrt(2^(prime(n) - 1)) = sqrt(2^A006093(n)) = sqrt(2^phi(prime(n))) = sqrt(2^A000010(A000040(n))).
Sum_{n>=1} 1/a(n) = A217054. - Amiram Eldar, Dec 23 2020
MATHEMATICA
Table[2^((Prime[n] - 1)/2), {n, 2, 25}] (* Amiram Eldar, Dec 23 2020 *)
CROSSREFS
Sequence in context: A307611 A053147 A128055 * A194810 A271216 A102000
KEYWORD
nonn
AUTHOR
Labos Elemer, May 22 2001
STATUS
approved

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Last modified June 15 02:53 EDT 2024. Contains 373402 sequences. (Running on oeis4.)