A331266 a(n) is the least divisor u of A331219(n) such that the binary representations of u and of A331219(n)/u have the same number of 0's and the same number of 1's.

1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 9, 10, 9, 10, 11, 11, 12, 11, 13, 13, 14, 15, 16, 17, 17, 18, 17, 18, 19, 19, 20, 17, 19, 18, 21, 21, 19, 20, 22, 19, 21, 23, 19, 21, 22, 22, 24, 21, 22, 23, 25, 25, 23, 26, 23, 25, 26, 27, 27, 28, 27, 29, 29, 30, 31, 32, 33, 33

Offset

1,2

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Formula

a(n) * A331267(n) = A331219(n).

Prog

(PARI) b=2; k=68; for (n=1, oo, fordiv (n, u, if (vecsort(digits(u, b))==vecsort(digits(n/u, b)), print1 (u", "); break (if (k--, 1, 2)))))

Crossrefs

Cf. A331219, A331267.

Sequence in context: A163296 A247971 A317334 * A172103 A123731 A247973

Adjacent sequences: A331263 A331264 A331265 * A331267 A331268 A331269

Keyword

nonn,base

Author

Rémy Sigrist, Jan 13 2020

Status

approved