OFFSET
1,1
LINKS
Index entries for linear recurrences with constant coefficients, signature (7, -7, 1)
FORMULA
a(n) = 7*a(n-1) - 7*a(n-2) + a(n-3).
a(n) = 6*a(n-1) - a(n-2) - 8.
a(n) = 2*(A001541(n) + 1). - Hugo Pfoertner, Feb 14 2021
G.f.: 4*x*(2 - 5*x + x^2)/((1 - x)*(1 - 6*x + x^2)). - Vaclav Kotesovec, Feb 14 2021
PROG
(PARI) default(realprecision, 120);
a(n) = round(sqrt(prod(j=1, n, prod(k=1, 2, 4*sin((2*j-1)*Pi/(2*n))^2+4*sin((2*k-1)*Pi/2)^2))));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Feb 14 2021
STATUS
approved