A048135 Tomahawk-constructible n-gons.

3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 24, 26, 27, 28, 30, 32, 34, 35, 36, 37, 38, 39, 40, 42, 45, 48, 51, 52, 54, 56, 57, 60, 63, 64, 65, 68, 70, 72, 73, 74, 76, 78, 80, 81, 84, 85, 90, 91, 95, 96, 97, 102, 104, 105, 108, 109, 111, 112

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

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

Crossrefs

Cf. A005109, A048136, A122254, A122255.

Programs

Python

from itertools import count, islice
from sympy import primefactors, totient
def A048135_gen(): # generator of terms
    yield from filter(lambda n: set(primefactors(totient(n))) <= {2,3}, count(3))
A048135_list = list(islice(A048135_gen(),66)) # Chai Wah Wu, Apr 02 2025

Formula

a(n) = A122254(n+2); A122255(a(n)) = 1. - Reinhard Zumkeller, Aug 29 2006