A068820 Ulam numbers that are primes.

2, 3, 11, 13, 47, 53, 97, 131, 197, 241, 409, 431, 607, 673, 739, 751, 983, 991, 1103, 1433, 1489, 1531, 1553, 1709, 1721, 2371, 2393, 2447, 2633, 2789, 2833, 2897, 3041, 3109, 3217, 3371, 3373, 3527, 3547, 3593, 3671, 3691, 4057, 4153, 4211, 4297, 4363

Offset: 1

Author

Naohiro Nomoto, Mar 29 2002

Keywords

• easy
• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..49221
• Shyam Sunder Gupta, Ulam Numbers. In: Exploring the Beauty of Fascinating Numbers. Springer Praxis Books(). Springer, Singapore, (2025).

Crossrefs

Cf. A002858.

Programs

Maple

# Function 'UlamList' is defined in A002858.
UlamPrimes := n -> select(k->isprime(k), UlamList(n)):
UlamPrimes(403); # Peter Luschny, Apr 05 2019