A288443 a(n) = (2n + 1)*2^(2n + 1); numbers k such that v(k)*2^v(k) = k, where v(n) = A007814(n) is 2-adic valuation of n.

2, 24, 160, 896, 4608, 22528, 106496, 491520, 2228224, 9961472, 44040192, 192937984, 838860800, 3623878656, 15569256448, 66571993088, 283467841536, 1202590842880, 5085241278464, 21440476741632, 90159953477632, 378231999954944, 1583296743997440, 6614661952700416, 27584547717644288, 114841790497947648

Offset

0,1

Links

Table of n, a(n) for n=0..25.

Formula

a(n) = (2n + 1)*2^(2n + 1).

a(n) = A036289(2n + 1).

a(n) = A098713(n) + 1.

a(n) = 2*A058962(n). - Joerg Arndt, Jun 25 2017

From Amiram Eldar, Jul 03 2020: (Start)

Sum_{n>=0} 1/a(n) = arctanh(1/2) = log(3)/2 (A156057).

Sum_{n>=0} (-1)^n/a(n) = arctan(1/2) (A073000). (End)

Prog

(Magma) [(2*n+1)*2^(2*n+1): n in [0..25]];
(PARI) a(n) = (2*n+1)<<(2*n+1) \\ Charles R Greathouse IV, Jul 07 2017

Crossrefs

Cf. A007814, A058962, A098713, A286683.

Odd bisection of A036289.

Cf. A073000, A156057.

Sequence in context: A189247 A234352 A241623 * A108476 A157053 A279853

Adjacent sequences: A288440 A288441 A288442 * A288444 A288445 A288446

Keyword

nonn,easy

Author

Juri-Stepan Gerasimov, Jun 24 2017

Status

approved