A353327 If n is a multiple of 3, then a(n) = 0, and if n is of the form 3k+r, with r = 1 or 2, then a(n) = 2*k + 3.
0, 3, 3, 0, 5, 5, 0, 7, 7, 0, 9, 9, 0, 11, 11, 0, 13, 13, 0, 15, 15, 0, 17, 17, 0, 19, 19, 0, 21, 21, 0, 23, 23, 0, 25, 25, 0, 27, 27, 0, 29, 29, 0, 31, 31, 0, 33, 33, 0, 35, 35, 0, 37, 37, 0, 39, 39, 0, 41, 41, 0, 43, 43, 0, 45, 45, 0, 47, 47, 0, 49, 49, 0, 51, 51, 0, 53, 53, 0, 55, 55, 0, 57, 57, 0, 59, 59, 0
Offset: 0
Links
- Index entries for linear recurrences with constant coefficients, signature (0,0,2,0,0,-1).
Programs
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PARI
A353327(n) = { my(r=(n%3)); if(!r,0,((2*((n-r)/3)) + 3)); };
Formula
a(n) = A353314(n) - n.
a(n) = A102899(3+n).
From Chai Wah Wu, Jul 27 2022: (Start)
a(n) = 2*a(n-3) - a(n-6) for n > 5.
G.f.: x*(-x^4 - x^3 + 3*x + 3)/(x^6 - 2*x^3 + 1). (End)