A371053 - OEIS

%I #13 Mar 21 2024 17:35:16

%S 210,2100,2110,2210,21000,21100,21110,22100,22110,22210,210000,211000,

%T 211100,211110,221000,221100,221110,222100,222110,222210,2100000,

%U 2110000,2111000,2111100,2111110,2210000,2211000,2211100,2211110,2221000,2221100,2221110

%N Ternary numbers consisting of a run of 2's, then a run of 1's, then a run of 0's.

%t Map[#[[1]] &, Select[Map[{#, Map[#[[1]] &, Split[IntegerDigits[#, 3]]] == {2, 1, 0}} &,

%t Range[0, 6000, 3]], #[[2]] &]] (* A371052 *)

%t ToExpression[Map[IntegerString[#, 3] &, %]]   (* this sequence *)

%t (* _Peter J. C. Moses_, Mar 06 2024 *)

%o (Python)

%o from itertools import count, islice

%o def A371053_gen(): # generator of terms

%o     return ((10**b*(10**a-1<<1)+10**b-1)//9*10**(l-a-b) for l in count(3) for a in range(1,l-1) for b in range(1,l-a))

%o A371053_list = list(islice(A371053_gen(),20)) # _Chai Wah Wu_, Mar 21 2024

%Y Cf. A007089, A371052.

%K nonn,base

%O 1,1

%A _Clark Kimberling_, Mar 17 2024