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Number of p-gons in cubic curve, where p = n-th prime.
2

%I #32 Jan 01 2023 04:29:23

%S 8,24,216,2376,381672,5163480,1010595960,14467313448,3059511345864,

%T 9938978525015640,148764065249108232,510526106263606993560,

%U 117943982401534505983800,1799331452450089752726504,421426396352475869646014856,1530747894615220749248821030680

%N Number of p-gons in cubic curve, where p = n-th prime.

%H M. Picquet, <a href="http://gallica.bnf.fr/ark:/12148/bpt6k433703n/f35.image">Applications de la représentation des courbes du troisième degré</a>, Journal de l'École Polytechnique, Paris, 35 (1884), 31-100.

%F a(n) = 8*(2^(p-2)+1)*(2^(p-1)-1)/p where p = n-th prime.

%o (PARI) a(n) = my(p=prime(n)); 8*(2^(p-2)+1)*(2^(p-1)-1)/p; \\ _Michel Marcus_, Dec 10 2014

%o (Magma) [8*(2^(p-2)+1)*(2^(p-1)-1)/p: p in PrimesUpTo(60)]; // _Vincenzo Librandi_, Dec 11 2014

%Y A subsequence of A005782. Cf. A200905.

%K nonn

%O 1,1

%A _N. J. A. Sloane_, Nov 23 2011