A394380 Number of totients below 2^n.

1, 2, 4, 7, 14, 26, 47, 87, 162, 297, 554, 1044, 1970, 3743, 7106, 13591, 26148, 50374, 97336, 188479, 365459, 709737, 1380640, 2688380, 5240975, 10229808, 19986100, 39083050, 76498140, 149846083, 293723009, 576152638, 1130853933, 2220916412, 4364104267

Offset

1,2

Links

Jud McCranie, Table of n, a(n) for n = 1..43

Formula

a(n) = A264810(2^n-1). - Jason Yuen, Mar 22 2026

Example

There are seven totient numbers (A002202) less than 16=2^4 (1, 2, 4, 6, 8, 10, and 12), so a(4)=7.

Prog

(PARI) a(n) = sum(i=1, 2^n-1, istotient(i)); \\ Michel Marcus, Mar 19 2026

Crossrefs

Cf. A000010, A002202, A221283, A264810, A394381.

Sequence in context: A026010 A088813 A347780 * A351013 A097596 A054191

Adjacent sequences: A394377 A394378 A394379 * A394381 A394382 A394383

Keyword

nonn

Author

Jud McCranie, Mar 18 2026

Status

approved