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A340326
a(n) = a(n-2) + (-1)^n*a(n-1) + n*(1-(-1)^n) with a(0) = a(1) = 1.
0
1, 1, 2, 5, 7, 8, 15, 7, 22, 3, 25, 0, 25, 1, 26, 5, 31, 8, 39, 7, 46, 3, 49, 0, 49, 1, 50, 5, 55, 8, 63, 7, 70, 3, 73, 0, 73, 1, 74, 5, 79, 8, 87, 7, 94, 3, 97, 0, 97, 1, 98, 5, 103, 8, 111, 7, 118, 3, 121, 0, 121, 1, 122, 5, 127, 8, 135, 7, 142, 3, 145, 0, 145, 1, 146, 5, 151
OFFSET
0,3
COMMENTS
If n > 0 then a(2n-1) = A021067(n).
a(n) = 0 if and only if n == -1 (mod 12).
FORMULA
G.f.: -(x^6+3*x^5-5*x^4-2*x^3+x^2-x-1)/(x^8-3*x^6+4*x^4-3*x^2+1). - Alois P. Heinz, Feb 07 2021
MATHEMATICA
a[0] = 1; a[1] = 1; a[n_] := a[n] = a[n - 2] + (-1)^n a[n - 1] + n (1 - (-1)^n); Array[a, 100]
CROSSREFS
Sequence in context: A275410 A139481 A363626 * A188341 A238364 A342730
KEYWORD
nonn,easy
AUTHOR
STATUS
approved