%I #13 Jul 10 2024 02:59:10

%S 0,0,1,0,0,1,3,3,4,0,0,1,0,0,1,3,3,4,9,9,10,9,9,10,12,12,13,0,0,1,0,0,

%T 1,3,3,4,0,0,1,0,0,1,3,3,4,9,9,10,9,9,10,12,12,13,27,27,28,27,27,28,

%U 30,30,31,27,27,28,27,27,28,30,30,31,36,36,37,36

%N a(n) is the least term t of A005836 such that n - t also belongs to A005836.

%C To compute a(n): in the ternary expansion of n, replace 1's by 0's and 2's by 1's.

%H Rémy Sigrist, <a href="/A374362/b374362.txt">Table of n, a(n) for n = 0..6561</a>

%F a(n) = A374361(n, 0).

%F a(n) = n - A374363(n).

%F a(n) >= 0 with equality iff n belongs to A374361.

%F a(n) = A005836(1 + A289814(n)).

%e The first terms, in decimal and in ternary, are:

%e n a(n) ter(n) ter(a(n))

%e -- ---- ------ ---------

%e 0 0 0 0

%e 1 0 1 0

%e 2 1 2 1

%e 3 0 10 0

%e 4 0 11 0

%e 5 1 12 1

%e 6 3 20 10

%e 7 3 21 10

%e 8 4 22 11

%e 9 0 100 0

%e 10 0 101 0

%e 11 1 102 1

%e 12 0 110 0

%e 13 0 111 0

%e 14 1 112 1

%e 15 3 120 10

%o (PARI) a(n) = fromdigits(apply(d -> [0, 0, 1][1+d], digits(n, 3)), 3)

%o (Python)

%o from gmpy2 import digits

%o def A374362(n): return int(digits(n,3).replace('1','0').replace('2','1'),3) # _Chai Wah Wu_, Jul 09 2024

%Y Cf. A005836, A289814, A374361.

%K nonn,base

%O 0,7

%A _Rémy Sigrist_, Jul 06 2024