A300557 a(n) is the concatenation of 1 written in base 2 once, 2 written in base 2 twice, ..., n written in base 2 n times.

1, 11010, 11010111111, 11010111111100100100100, 11010111111100100100100101101101101101, 11010111111100100100100101101101101101110110110110110110, 11010111111100100100100101101101101101110110110110110110111111111111111111111

Offset

1,2

Links

Seiichi Manyama, Table of n, a(n) for n = 1..21

Mathematica

A300557[n_] := FromDigits[StringJoin[Table[StringRepeat[IntegerString[m, 2], m], {m, n}]]];
Array[A300557, 8] (* Paolo Xausa, Jan 15 2026 *)

Prog

(Python)
def a(n): return int("".join((bin(i)[2:])*i for i in range(1, n+1)))
print([a(n) for n in range(1, 8)]) # Michael S. Branicky, Jan 15 2026

Crossrefs

Cf. A007088, A098129, A300558.

Sequence in context: A251873 A267038 A267293 * A181319 A267811 A267934

Adjacent sequences: A300554 A300555 A300556 * A300558 A300559 A300560

Keyword

nonn,base,easy

Author

Seiichi Manyama, Mar 08 2018

Status

approved