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A267185
Column 2 of the square array in A267181.
0
0, 1, 0, 4, 2, 5, 3, 6, 4, 7, 5, 8, 6, 9, 7, 10, 8, 11, 9, 12, 10, 13, 11, 14, 12, 15, 13, 16, 14, 17, 15, 18, 16, 19, 17, 20, 18, 21, 19, 22, 20, 23, 21, 24, 22, 25, 23, 26, 24, 27, 25, 28, 26, 29, 27, 30, 28, 31, 29, 32, 30, 33, 31, 34, 32, 35, 33, 36, 34, 37, 35
OFFSET
0,4
FORMULA
Conjectures from Colin Barker, Jan 29 2016: (Start)
a(n) = (2*n-5*((-1)^n-1))/4 for n>2.
a(n) = n/2 for n>2 and even.
a(n) = (n+5)/2 for n>2 and odd.
a(n) = a(n-1)+a(n-2)-a(n-3) for n>5.
G.f.: x*(1-x+3*x^2-x^3-x^4) / ((1-x)^2*(1+x)).
(End)
CROSSREFS
Cf. A267181.
Sequence in context: A123152 A309567 A243855 * A065187 A185511 A199855
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 17 2016
STATUS
approved