a(n) is the hafnian of the 2n X 2n symmetric matrix whose element M_{i,j} equals phi(abs(i-j)).

A354865

a(n) is the hafnian of the 2n X 2n symmetric matrix whose element M_{i,j} equals phi(abs(i-j)).

Terms

    a(0) =1a(1) =1a(2) =4a(3) =49a(4) =1193a(5) =50228a(6) =3098989a(7) =271913937a(8) =31382686354

External references