OFFSET
0,3
COMMENTS
FORMULA
a(n) = -A(n) + 3*B(n) - (n - 1), where A(n) = A278040(n). For a proof see the W. Lang link in A080843, Proposition 8, eq. (46).
a(n) = Sum_{k=1..n-1} d(k), where d is the tribonacci sequence on the alphabet {1,2,0}. - Michel Dekking, Oct 08 2019
EXAMPLE
n = 3: B(3) = 6, t = {0, 1, 0, 2, 0, 1, 0, ...} which sums to 4 = a(3) = -12 + 3*6 - 2, because A(3) = 12.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Jan 02 2019
EXTENSIONS
Name changed by Michel Dekking, Oct 07 2019
STATUS
approved