OFFSET
1,2
COMMENTS
Corresponding values of m are given in A166929 - see it for further details.
Terms with positive a, b are given in A167438.
This is the absolute value of a bisection of a generalized Somos-5 sequence. - Michael Somos, Nov 04 2022
PROG
(PARI) {a(n) = local(x, v); n = abs(2*n+1); (x = m-> v[abs(m)+1]); v = vector(max(3, n+1), m, 1); v[3] = -3; for(k=3, n, v[k+1] = -(13*x(k-1)*x(k-4) + 42*x(k-2)*x(k-3)) / x(k-5)); abs(x(n))}; /* Michael Somos, Nov 04 2022 */
CROSSREFS
KEYWORD
nonn
AUTHOR
Max Alekseyev, Nov 03 2009
STATUS
approved