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

1,2

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

Links

Table of n, a(n) for n=1..55.

Formula

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

Prog

(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

Crossrefs

Cf. A002144, A006005, A008578, A020668.

Sequence in context: A175768 A351535 A002144 * A319287 A192592 A357218

Adjacent sequences: A280081 A280082 A280083 * A280085 A280086 A280087

Keyword

nonn,easy,less

Author

Juri-Stepan Gerasimov, Dec 25 2016

Status

approved