OFFSET
0,9
COMMENTS
The sequence is similar to Somos-8 but all of the terms are integers.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..252
FORMULA
a(n) = a(7-n) for all n in Z.
a(n)*a(n+8) = a(n+1)*a(n+7) + a(n+2)*a(n+6) - a(n+3)*a(n+5) + a(n+4)^2 for all n in Z.
a(n)*a(n+9) = -a(n+1)*a(n+8) + 3*a(n+2)*a(n+7) + a(n+3)*a(n+6) + a(n+4)*a(n+5) for all n in Z.
0 = + a(n+6)*a(n+3)*a(n) - a(n+6)*a(n+2)*a(n+1) - a(n+5)*a(n+4)*a(n) - a(n+5)*a(n+3)*a(n+1) + 2*a(n+5)*a(n+2)^2 + 2*a(n+4)^2*a(n+1) - 3*a(n+4)*a(n+3)*a(n+2) + a(n+3)^3 for all n in Z.
PROG
(PARI) {a(n) = my(v); if( n<0, n=7-n); if( n<8, 1, n++; v=vector(n, k, 1); for( k=9, n, v[k] = (v[k-1]*v[k-7] + v[k-2]*v[k-6] - v[k-3]*v[k-5] + v[k-4]^2) / v[k-8]); v[n])};
CROSSREFS
KEYWORD
nonn
AUTHOR
Michael Somos, Mar 03 2020
STATUS
approved