A026154 a(n) = T(n,n-3), where T is the array in A026148.
1, 3, 11, 35, 111, 343, 1049, 3177, 9559, 28611, 85293, 253461, 751296, 2222442, 6563598, 19359022, 57038247, 167911721, 493972165, 1452419661, 4268753126, 12542145548, 36841741320, 108202146520, 317748977715, 933052724721, 2739805981773
Offset: 3
Keywords
Crossrefs
First differences of A026328.
Formula
Conjecture: (n+9)*a(n) +(-7*n-47)*a(n-1) +(13*n+51)*a(n-2) +(5*n+37)*a(n-3) +2*(-13*n-6)*a(n-4) +2*(n-13)*a(n-5) +12*(n-4)*a(n-6)=0. - R. J. Mathar, Jun 23 2013