cp's OEIS Frontend

A058058 Generalized Somos-7 sequence: a(n)*a(n+7) = 3*a(n+1)*a(n+6) - 4*a(n+2)* a(n+5) + 4*a(n+3)*a(n+4).

%I A058058 #10 Sep 08 2022 08:45:02
%S A058058 1,1,1,1,1,1,1,3,9,19,33,131,681,3921,23801,132881,598121,7466321,
%T A058058 141401273,1865484899,19358862929,314151573363,7831607063961,
%U A058058 237725833277411,8937694547422641,293153245305595201,7098035759907924561,310194702846756799041,35075042744420641281841
%N A058058 Generalized Somos-7 sequence: a(n)*a(n+7) = 3*a(n+1)*a(n+6) - 4*a(n+2)* a(n+5) + 4*a(n+3)*a(n+4).
%D A058058 N. Elkies, posting to the NMBRTHRY(AT)LISTSERV.NODAK.EDU newsgroup, Nov. 2000.
%H A058058 G. C. Greubel, <a href="/A058058/b058058.txt">Table of n, a(n) for n = 1..170</a>
%t A058058 a[1] =a[2] =a[3] =a[4] =a[5] =a[6] =a[7] =1; a[n_]:= a[n] = (3*a[n-1]*a[n-6] - 4*a[n-2]*a[n-5] + 4*a[n-3]*a[n-4])/a[n-7]; Table[ a[n], {n, 1, 35}]
%o A058058 (PARI) {a(n) = if (n <=7, 1, (3*a(n-1)*a(n-6) - 4*a(n-2)*a(n-5) + 4*a(n-3)*a(n-4))/a(n-7))};
%o A058058 for(n=1, 30, print1(a(n), ", ")) \\ _G. C. Greubel_, Feb 21 2018
%o A058058 (Magma) I:=[1,1,1,1,1,1,1]; [n le 7 select I[n] else (3*Self(n-1)*Self(n-6) - 4*Self(n-2)*Self(n-5) + 4*Self(n-3)*Self(n-4))/Self(n-7): n in [1..30]]; // _G. C. Greubel_, Feb 21 2018
%Y A058058 Cf. A006720, A006721, A006722 and A006723.
%K A058058 nonn
%O A058058 1,8
%A A058058 _Robert G. Wilson v_, Nov 20 2000