A382670 -id:A382670 - cp's OEIS frontend

A382653 Numbers k such that a regular k-gon (k>=3) cannot be constructed with a compass, straightedge and an angle quinsector.

7, 9, 13, 14, 18, 19, 21, 23, 26, 27, 28, 29, 31, 35, 36, 37, 38, 39, 42, 43, 45, 46, 47, 49, 52, 53, 54, 56, 57, 58, 59, 61, 62, 63, 65, 67, 69, 70, 71, 72, 73, 74, 76, 77, 78, 79, 81, 83, 84, 86, 87, 89, 90, 91, 92, 93, 94, 95, 97, 98, 99, 103, 104, 105, 106

Offset: 1

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Chai Wah Wu, Apr 02 2025

nonn

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

Cf. A048135, A048136, A382670.

from itertools import count, islice
from sympy import primefactors, totient
def A382653_gen(): # generator of terms
    yield from filter(lambda n: not set(primefactors(totient(n))) <= {2,5}, count(3))
A382653_list = list(islice(A382653_gen(),30))

cp's OEIS Frontend

A382653 Numbers k such that a regular k-gon (k>=3) cannot be constructed with a compass, straightedge and an angle quinsector.

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