A167843 Obtuse-angled primes.

113, 127, 137, 139, 149, 157, 167, 179, 199, 211, 223, 227, 229, 233, 239, 257, 269, 277, 311, 331, 337, 347, 349, 359, 367, 379, 389, 421, 431, 433, 443, 449, 457, 467, 479, 499, 521, 541, 557, 569, 577, 599, 631, 641, 643, 653, 661, 677, 733, 743, 751, 761

Offset: 1

Author

Omar E. Pol, Nov 13 2009

Keywords

• base
• nonn

Comments

Primes in A135603.

Primes whose structure of digits represents an obtuse angle. The vertex is an internal digit. In the graphic representation the points are connected by imaginary line segments from left to right.

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..914

Crossrefs

Cf. A134811, A134951, A134971, A135603, A167841, A167842, A167844, A167845, A167846, A167853.

Programs

Python

# uses agen() from A135603
from sympy import isprime
g = filter(isprime, agen())
print([next(g) for n in range(1, 53)]) # Michael S. Branicky, Aug 03 2022

Extensions

a(12) and beyond from Michael S. Branicky, Aug 03 2022