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A025473 a(1) = 1; for n > 1, a(n) = prime root of n-th prime power (A000961). +0
15
1, 2, 3, 2, 5, 7, 2, 3, 11, 13, 2, 17, 19, 23, 5, 3, 29, 31, 2, 37, 41, 43, 47, 7, 53, 59, 61, 2, 67, 71, 73, 79, 3, 83, 89, 97, 101, 103, 107, 109, 113, 11, 5, 127, 2, 131, 137, 139, 149, 151, 157, 163, 167, 13, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239 (list; graph; listen)
OFFSET

1,2

COMMENT

This sequence is related to the cyclotomic sequences A013595 and A020500, leading to the procedure used in the Mathematica program. - Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Jul 08 2008

REFERENCES

Paul J. McCarthy, Algebraic Extensions of Fields,Dover books, 1976, page s 40, 69

Weisstein, Eric W. "Cyclotomic Polynomial." http://mathworld.wolfram.com/CyclotomicPolynomial.html

LINKS

David Wasserman, Table of n, a(n) for n=1..1000

FORMULA

a(n) = A006530(A000961(n)) = A020639(A000961(n)). - David Wasserman (wasserma(AT)spawar.navy.mil), Feb 16 2006

MATHEMATICA

a = Join[{1}, Flatten[Table[If[PrimeQ[Apply[Plus, CoefficientList[Cyclotomic[n, x], x]]], Apply[Plus, CoefficientList[Cyclotomic[n, x], x]], {}], {n, 1, 1000}]]] - Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Jul 08 2008

CROSSREFS

Cf. A013595 and A020500.

Sequence in context: A135875 A097448 A133684 this_sequence A092556 A092550 A058977

Adjacent sequences: A025470 A025471 A025472 this_sequence A025474 A025475 A025476

KEYWORD

easy,nonn,nice

AUTHOR

David W. Wilson (davidwwilson(AT)comcast.net)

EXTENSIONS

Corrected offset David Wasserman (dwasserm(AT)earthlink.net), Dec 22 2008

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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