A371054 Numbers whose ternary representation consists of a run of 1's, then a run of 0's, then a run of 2's.

11, 29, 35, 38, 83, 89, 107, 110, 116, 119, 245, 251, 269, 323, 326, 332, 350, 353, 359, 362, 731, 737, 755, 809, 971, 974, 980, 998, 1052, 1055, 1061, 1079, 1082, 1088, 1091, 2189, 2195, 2213, 2267, 2429, 2915, 2918, 2924, 2942, 2996, 3158, 3161, 3167, 3185

Offset

1,1

Comments

a(n) == 2 (mod 3) for all n.

Links

Table of n, a(n) for n=1..49.

Mathematica

Map[#[[1]] &, Select[Map[{#, Map[#[[1]] &, Split[IntegerDigits[#, 3]]] == {1, 0, 2}} &,
Range[2, 4000, 3]], #[[2]] &]]  (* this sequence *)
ToExpression[Map[IntegerString[#, 3] &, %]]  (* A371055 *)
(* Peter J. C. Moses, Mar 06 2024 *)

Prog

(Python)
from itertools import count, islice
def A371054_gen(): # generator of terms
    return (3**(l-a)*(3**a-1>>1)+3**b-1 for l in count(3) for a in range(1, l-1) for b in range(1, l-a))
A371054_list = list(islice(A371054_gen(), 20)) # Chai Wah Wu, Mar 20 2024

Crossrefs

Cf. A007089, A371055.

Sequence in context: A124110 A153768 A371106 * A360181 A092194 A134307

Adjacent sequences: A371051 A371052 A371053 * A371055 A371056 A371057

Keyword

nonn,base

Author

Clark Kimberling, Mar 19 2024

Status

approved