cp's OEIS Frontend

A271831 Somos's sequence {a(6,n)} defined in comment in A018896: a(0)=a(1)= ... = a(13) = 1; for n>=14, a(n) = (a(n-1)*a(n-13) + a(n-7)^2)/a(n-14).

%I A271831 #44 Feb 16 2025 08:33:33
%S A271831 1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,3,4,5,6,7,8,12,21,37,62,98,147,358,609,
%T A271831 959,1541,2618,4655,8407,28631,81011,186528,376741,706041,1280174,
%U A271831 3598503,8411236,24021605,74880071,219318499,580374907,1400227135,6308924342
%N A271831 Somos's sequence {a(6,n)} defined in comment in A018896: a(0)=a(1)= ... = a(13) = 1;  for n>=14, a(n) = (a(n-1)*a(n-13) + a(n-7)^2)/a(n-14).
%H A271831 Seiichi Manyama, <a href="/A271831/b271831.txt">Table of n, a(n) for n = 0..416</a>
%H A271831 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SomosSequence.html">Somos Sequence</a>
%t A271831 a[n_ /; 0 <= n <= 14] = 1; a[n_]:= a[n] = (a[n-1]*a[n-13] + a[n-7]^2)/a[n -14]; Table[a[n], {n,0,50}] (* _G. C. Greubel_, Feb 21 2018 *)
%o A271831 (PARI) {a(n) = if(n<= 14, 1, (a(n-1)*a(n-13) + a(n-7)^2)/a(n-14))};
%o A271831 for(n=1,50, print1(a(n), ", ")) \\ _G. C. Greubel_, Feb 21 2018
%o A271831 (Magma) [n le 14 select 1 else (Self(n-1)*Self(n-13) + Self(n-7)^2)/Self(n-14): n in [1..50]]; // _G. C. Greubel_, Feb 21 2018
%Y A271831 Cf. A018896, A006125, A006720, A102276, A271341, A271835, A271837, A271838, A271839.
%K A271831 nonn
%O A271831 0,15
%A A271831 _Vladimir Shevelev_ and _Peter J. C. Moses_, Apr 15 2016