A330740 a(n) = min(n, A004488(n)), where A004488(n) is base-3 sum n+n without carries.

0, 1, 1, 3, 4, 5, 3, 5, 4, 9, 10, 11, 12, 13, 14, 15, 16, 17, 9, 11, 10, 15, 17, 16, 12, 14, 13, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 27, 29, 28, 33, 35, 34, 30, 32, 31, 45, 47, 46, 51, 53, 52, 48, 50, 49, 36, 38, 37, 42, 44, 43, 39, 41, 40, 81

Offset: 0

Author

Antti Karttunen, Jan 11 2020

Keywords

• nonn
• base

Comments

After the initial zero, sequence contains only terms of A132141, each appearing exactly twice.

Links

• Antti Karttunen, Table of n, a(n) for n = 0..59048

Crossrefs

Cf. A004488, A132141.

Central diagonal of A325825 (after the initial zero).

Programs

PARI

A330740(n) = min(n,subst(Pol(apply(x->(3-x)%3, digits(n, 3)), 'x), 'x, 3));

Formula

a(n) = min(n, A004488(n)).