A363789 a(n) is the smallest primitive binary Niven number (A363787) whose binary representation is ending with n zeros.

1, 6, 60, 2040, 1048560, 137438953440, 1180591620717411303360, 43556142965880123323311949751266331066240, 29642774844752946028434172162224104410437116074403984394101141506025761187823360

Offset: 0

Author

Amiram Eldar, Jun 22 2023

Keywords

• nonn
• easy
• base

Comments

The least term k of A363787 such that A007814(k) = n.

Also, the least binary Niven number (A049445) with a binary weight (A000120) that equals 2^n.

The next term, a(9) = 6.864... * 10^156, is too long to include in the Data section.

Links

• Amiram Eldar, Table of n, a(n) for n = 0..11

Crossrefs

Subsequence of A049445, A143115 and A363787.

Cf. A000120, A007814, A066524, A358256 (decimal analog).

Programs

Mathematica

a[n_] := (2^(2^n)-1) * 2^n; Array[a, 9, 0]

PARI

a(n) = (2^(2^n)-1) * 2^n;

Formula

a(n) = (2^(2^n)-1) * 2^n = A066524(2^n).

a(n) = A143115(2^n).