OFFSET
0,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..500
FORMULA
G.f: (1/4)*x^3 - (1/8)*x^2 - 1/16 + (x^4 + (3/4)*x^3 - (1/2)*x^2 - (3/16)*x + 1/16)*F(x) = 0. [From GUESSS]
From David Scambler, Jun 17 2010: (Start)
a(n) = (17*4^n + 5*(2*(-1)^n-1)*2^n - 7*(-1)^n)/15.
(End)
EXAMPLE
a(0) = 1, a(1) = 3, a(2) = 6 + 6 + 7 = 19.
PROG
(PARI) seq(n)={my(a=vector(n+1), f=0, p=0, k=1, s=0); while(k<=#a, my(b=bitxor(p+1, p)); f=bitxor(f, b); p=bitxor(p, bitand(b, f)); if(p>2^k, a[k]=s; k++; s=0); s+=p); a} \\ Andrew Howroyd, Mar 03 2020
(PARI) a(n) = {(17*4^n + 5*(2*(-1)^n-1)*2^n - 7*(-1)^n)/15} \\ Andrew Howroyd, Mar 03 2020
KEYWORD
nonn
AUTHOR
David Scambler, Jun 09 2010
EXTENSIONS
Terms a(16) and beyond from Andrew Howroyd, Mar 03 2020
STATUS
approved