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 A130614 a(n) = p^(p-2), where p = prime(n). 2
 1, 3, 125, 16807, 2357947691, 1792160394037, 2862423051509815793, 5480386857784802185939, 39471584120695485887249589623, 3053134545970524535745336759489912159909 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Number of labeled trees on p(n) nodes, where p(n) is the n-th prime. Let p = prime(n). For n >= 2, (-1)^((p-1)/2) * a(n) is the discriminant of the p-th cyclotomic polynomial. - Jianing Song, May 10 2021 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..77 FORMULA a(n) = A000272(A000040(n)). For n >= 2, (-1)^((p-1)/2) * a(n) = A004124(p), where p = prime(n). - Jianing Song, May 10 2021 MATHEMATICA Table[Prime@n^(Prime@n - 2), {n, 20}] (* Vincenzo Librandi, Mar 27 2014 *) #^(#-2)&/@Prime[Range[10]] (* Harvey P. Dale, Oct 18 2016 *) PROG (Magma) [n^(n-2) : n in [2..40] | IsPrime(n)]; (Magma) [p^(p-2): p in PrimesUpTo(50)]; // Vincenzo Librandi, Mar 27 2014 (PARI) a(n) = my(p=prime(n)); p^(p-2) \\ Felix Fröhlich, May 10 2021 CROSSREFS Cf. A000040, A000272, A004124, A036878. Sequence in context: A219010 A037118 A085531 * A114877 A152859 A241647 Adjacent sequences: A130611 A130612 A130613 * A130615 A130616 A130617 KEYWORD easy,nonn AUTHOR Jonathan Vos Post, Jun 18 2007 EXTENSIONS Name edited by Felix Fröhlich, May 10 2021 STATUS approved

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Last modified June 7 11:34 EDT 2023. Contains 363157 sequences. (Running on oeis4.)