A395274 - OEIS

%I #7 Apr 18 2026 12:52:16

%S 1,119,83281,145800359,476505209761,2502838476144599,

%T 19280997072330355441,204797011339726937324039,

%U 2868518098265007506767936321,51227334488880915770157520378679,1136077852491071055019123212221408401,30631820404953071010639678870096430748519

%N a(n) = (2*n)! * [x^(2*n)] cos(3*x) * cos(4*x) / cos(12*x).

%F a(n) = (-1)^n * (49^n + 1)/2 - Sum_{k=0..n-1} (-144)^(n-k) * binomial(2*n,2*k) * a(k).

%o (PARI) a_vector(n, s=3, t=4) = my(v=vector(n+1)); for(i=0, n, v[i+1]=(-1)^i*((s+t)^(2*i)+(s-t)^(2*i))/2-sum(j=0, i-1, (-(s*t)^2)^(i-j)*binomial(2*i, 2*j)*v[j+1])); v;

%Y Cf. A352977.

%K nonn

%O 0,2

%A _Seiichi Manyama_, Apr 18 2026