A138890 - OEIS

%I #13 Sep 17 2024 10:36:35

%S 6,8,10,11,13,14,15,17,18,19,20,22,23,24,25,26,27,29,30,31,32,33,34,

%T 35,36,38,39,40,41,42,43,44,45,46,47,48,50,51,52,53,54,55,56,57,58,59,

%U 60,61,62,63,64,66,67,68,69,70,71,72,73,74

%N Non-Padovan numbers.

%C Natural numbers that are not in the Padovan sequence A000931.

%H Michael De Vlieger, <a href="/A138890/b138890.txt">Table of n, a(n) for n = 1..10000</a>

%H Chai Wah Wu, <a href="https://arxiv.org/abs/2409.05844">Algorithms for complementary sequences</a>, arXiv:2409.05844 [math.NT], 2024.

%t Complement[Range[0, Max[#]], #] &@ Union@ LinearRecurrence[{0, 1, 1}, {1, 0, 0}, 23] (* _Michael De Vlieger_, Sep 17 2024 *)

%o (Python)

%o def A138890(n):

%o     def f(x):

%o         if x<=1: return n+1

%o         a, b, c, d = 1, 1, 1, 0

%o         while c<=x:

%o             a, b, c = b, c, a+b

%o             d += 1

%o         return n+d-1

%o     m, k = n, f(n)

%o     while m != k: m, k = k, f(k)

%o     return m # _Chai Wah Wu_, Sep 10 2024

%Y Cf. A000931, A001690, A062289, A092460, A134816, A138836, A138888, A138891.

%K easy,nonn

%O 1,1

%A _Omar E. Pol_, Apr 05 2008