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A115059
a(n+4) = a(n+3)+a(n+1)+a(n)+k(n), where k(n) = 0, 1, 0, or -1 according to n mod 4.
1
0, 0, 1, 1, 1, 3, 5, 6, 10, 19, 30, 45, 74, 124, 199, 317, 515, 839, 1355, 2186, 3540, 5735, 9276, 15001, 24276, 39288, 63565, 102841, 166405, 269259, 435665, 704910, 1140574, 1845499, 2986074, 4831557, 7817630, 12649204, 20466835, 33116021
OFFSET
0,6
COMMENTS
a(n) + 2a(n+2) + a(n+4) is the (n+4)th Fibonacci number.
LINKS
MATHEMATICA
nxt[{n_, a_, b_, c_, d_}]:={n+1, b, c, d, a+b+d+Which[Mod[n+1, 4] == 0, 0, Mod[ n+1, 4] == 1, 1, Mod[n+1, 4]==2, 0, True, -1]}; NestList[nxt, {3, 0, 0, 1, 1}, 40][[All, 2]] (* Harvey P. Dale, Mar 24 2022 *)
CROSSREFS
Sequence in context: A194466 A270416 A290269 * A250218 A092835 A335403
KEYWORD
nonn
AUTHOR
M. N. Deshpande (dpratap_ngp(AT)sancharnet.in), Feb 28 2006
EXTENSIONS
Edited by Don Reble, Mar 14 2006
STATUS
approved