OFFSET
1,3
COMMENTS
A subsequence of A348897, i.e. each term of this sequence has the form (x + y)*(x^2 + y^2).
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,3,-3,-3,3,1,-1).
FORMULA
From Stefano Spezia, Nov 11 2021: (Start)
a(n) = ((5 + 3*n - n^2)*(1 - (-1)^n) + 2*n^3)/16 for n > 1.
a(n) = a(n-1) + 3*a(n-2) - 3*a(n-3) - 3*a(n-4)+ 3*a(n-5) + a(n-6) - a(n-7) for n > 8. (End)
MATHEMATICA
Join[{0}, LinearRecurrence[{1, 3, -3, -3, 3, 1, -1}, {1, 4, 8, 15, 27, 40, 64}, 47]] (* Stefano Spezia, Nov 11 2021 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Peter Luschny, Nov 10 2021
STATUS
approved