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A371056 Numbers whose ternary representation consists of a run of 2's, then a run of 0's, then a run of 1's. 1
19, 55, 58, 73, 163, 166, 175, 217, 220, 235, 487, 490, 499, 526, 649, 652, 661, 703, 706, 721, 1459, 1462, 1471, 1498, 1579, 1945, 1948, 1957, 1984, 2107, 2110, 2119, 2161, 2164, 2179, 4375, 4378, 4387, 4414, 4495, 4738, 5833, 5836, 5845, 5872, 5953, 6319 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(n) == 1 mod 3 for all n.
LINKS
MATHEMATICA
Map[#[[1]] &, Select[Map[{#, Map[#[[1]] &, Split[IntegerDigits[#, 3]]] == {2, 0, 1}} &, Range[1, 36000, 3]], #[[2]] &]] (* this sequence *)
ToExpression[Map[IntegerString[#, 3] &, %]] (* A371057 *)
(* Peter J. C. Moses, Mar 06 2024 *)
PROG
(Python)
from itertools import count, islice
def A371056_gen(): # generator of terms
return (3**(l-a)*(3**a-1)+(3**b-1>>1) for l in count(3) for a in range(1, l-1) for b in range(1, l-a))
A371056_list = list(islice(A371056_gen(), 20)) # Chai Wah Wu, Mar 30 2024
CROSSREFS
Sequence in context: A288144 A051871 A371110 * A044121 A044502 A069131
KEYWORD
nonn,base
AUTHOR
Clark Kimberling, Mar 22 2024
STATUS
approved

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Last modified July 22 13:05 EDT 2024. Contains 374499 sequences. (Running on oeis4.)