login
Numbers m such that the tribonacci representation of m (A278038) ends in an even number of 0's.
3

%I #12 Mar 04 2022 04:20:12

%S 1,3,4,5,8,10,11,12,13,14,16,17,18,21,23,25,27,28,29,32,34,35,36,37,

%T 38,40,41,42,44,45,47,48,49,52,54,55,56,57,58,60,61,62,65,67,69,71,72,

%U 73,76,78,79,80,82,84,85,86,89,91,92,93,94,95,97,98,99,102,104,106,108,109,110,113,115,116,117,118,119,121

%N Numbers m such that the tribonacci representation of m (A278038) ends in an even number of 0's.

%C The asymptotic density of this sequence is c/(c+1) = 0.647798..., where c = 1.839286... (A058265) is the tribonacci constant. - _Amiram Eldar_, Mar 04 2022

%H Amiram Eldar, <a href="/A308197/b308197.txt">Table of n, a(n) for n = 1..10000</a>

%t t[1] = 1; t[2] = 2; t[3] = 4; t[n_] := t[n] = t[n - 1] + t[n - 2] + t[n - 3]; q[n_] := Module[{s = {}, m = n, k}, While[m > 0, k = 1; While[t[k] <= m, k++]; k--; AppendTo[s, k]; m -= t[k]; k = 1]; EvenQ[Min[s] - 1]]; Select[Range[0, 121], q] (* _Amiram Eldar_, Mar 04 2022 *)

%Y Cf. A278038, A278045, A308198, A058265.

%K nonn,base

%O 1,2

%A _N. J. A. Sloane_, Jun 22 2019