OFFSET
1,2
FORMULA
Conjectures from Chai Wah Wu, Apr 15 2024: (Start)
a(n) = a(n-1) + a(n-2) + a(n-3) - a(n-4) - a(n-5) for n > 6.
G.f.: x*(-2*x^5 - 3*x^4 + 3*x^2 + 2*x + 1)/((x - 1)*(x^2 + x - 1)*(x^2 + x + 1)). (End)
PROG
(PARI) L(n) = fibonacci(n+1)+fibonacci(n-1); \\ A000204
T(n, k) = if (k<n, return(0)); if (n==k, return(L(n))); if (k==2*n, return((-1)^(n+1))); return(0); \\ A138123
lista(nn) = my(list = List()); for (k=1, nn, my(i=k, j=1, s=0); for (m=1, k, s += T(i, j); i--; j++; ); if ((s>0) && (s%2), listput(list, s)); ); Set(list);
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul Curtz, Sep 18 2008
EXTENSIONS
Edited by N. J. A. Sloane, Dec 10 2008
More terms from Michel Marcus, Apr 16 2024
STATUS
approved