A280084 1 together with the Pythagorean primes.

1, 5, 13, 17, 29, 37, 41, 53, 61, 73, 89, 97, 101, 109, 113, 137, 149, 157, 173, 181, 193, 197, 229, 233, 241, 257, 269, 277, 281, 293, 313, 317, 337, 349, 353, 373, 389, 397, 401, 409, 421, 433, 449, 457, 461, 509, 521, 541, 557, 569, 577, 593, 601, 613, 617

Offset: 1

Author

Juri-Stepan Gerasimov, Dec 25 2016

Keywords

• nonn
• easy
• less

Comments

Positive noncomposite numbers of the form 4k + 1.

Positive noncomposite numbers in A020668.

Essentially the same as A002313 and A002144. - R. J. Mathar, Jan 04 2017

Crossrefs

Cf. A002144, A006005, A008578, A020668.

Programs

Magma

[1] cat [a: n in [0..200] | IsPrime(a) where a is 4*n + 1 ];

PARI

is(n)=if(isprime(n), n%4==1, n==1) \\ Charles R Greathouse IV, Oct 10 2018

Formula

A002144 UNION {1}. - R. J. Mathar, Jan 04 2017