A382670 Numbers k such that a regular k-gon (k>=3) can be constructed with a compass, straightedge and an angle quinsector.

3, 4, 5, 6, 8, 10, 11, 12, 15, 16, 17, 20, 22, 24, 25, 30, 32, 33, 34, 40, 41, 44, 48, 50, 51, 55, 60, 64, 66, 68, 75, 80, 82, 85, 88, 96, 100, 101, 102, 110, 120, 123, 125, 128, 132, 136, 150, 160, 164, 165, 170, 176, 187, 192, 200, 202, 204, 205, 220, 240

Offset

1,1

Links

Table of n, a(n) for n=1..60.

Andrew M. Gleason, Angle Trisection, the Heptagon and the Triskaidecagon, American Mathematical Monthly, 95 (1988), 185-194.

Prog

(Python)
from itertools import count, islice
from sympy import primefactors, totient
def A382670_gen(): # generator of terms
    yield from filter(lambda n: set(primefactors(totient(n))) <= {2, 5}, count(3))
A382670_list = list(islice(A382670_gen(), 70))

Crossrefs

Cf. A048135, A048136, A382653.

Sequence in context: A039031 A047309 A121502 * A180644 A202110 A267858

Adjacent sequences: A382667 A382668 A382669 * A382671 A382672 A382673

Keyword

nonn

Author

Chai Wah Wu, Apr 02 2025

Status

approved