A376295 The binary expansion of a(n) is the reversal of the concatenation of the binary expansions of 1,...,n.

1, 3, 27, 59, 1339, 7483, 122171, 253243, 19127611, 186899771, 7166221627, 32936025403, 1544764513595, 16937927302459, 544703508634939, 1107653462056251, 307352428123249979, 5495499198854061371, 466664101041592851771, 3418143152835121110331, 400096927713885319060795

Offset

1,2

Links

Paolo Xausa, Table of n, a(n) for n = 1..400

Formula

a(n) = A030101(A047778(n)).

Example

For n = 4 a(4) = 59 because:
Concatenation:  1 10 11 100
Reversed order: 00111011
And 00111011 in base 10 is 59.

Mathematica

IntegerReverse[Module[{n = 1}, NestList[#*2^BitLength[++n] + n &, 1, 25]], 2] (* Paolo Xausa, Sep 30 2024 *)

Prog

(Python)
a = lambda n: int("".join(bin(x)[2:] for x in range(1, n+1))[::-1], 2)
print([a(n) for n in range(1, 22)])

Crossrefs

Cf. A030101, A047778.

Sequence in context: A201276 A053360 A176963 * A204046 A305094 A120117

Adjacent sequences: A376292 A376293 A376294 * A376296 A376297 A376298

Keyword

nonn,base,easy

Author

Darío Clavijo, Sep 19 2024

Status

approved