This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A280084 #21 Sep 08 2022 08:46:18
%S A280084 1,5,13,17,29,37,41,53,61,73,89,97,101,109,113,137,149,157,173,181,
%T A280084 193,197,229,233,241,257,269,277,281,293,313,317,337,349,353,373,389,
%U A280084 397,401,409,421,433,449,457,461,509,521,541,557,569,577,593,601,613,617
%N A280084 1 together with the Pythagorean primes.
%C A280084 Positive noncomposite numbers of the form 4k + 1.
%C A280084 Positive noncomposite numbers in A020668.
%C A280084 Essentially the same as A002313 and A002144. - _R. J. Mathar_, Jan 04 2017
%F A280084 A002144 UNION {1}. - _R. J. Mathar_, Jan 04 2017
%o A280084 (Magma) [1] cat [a: n in [0..200] | IsPrime(a) where a is 4*n + 1 ];
%o A280084 (PARI) is(n)=if(isprime(n), n%4==1, n==1) \\ _Charles R Greathouse IV_, Oct 10 2018
%Y A280084 Cf. A002144, A006005, A008578, A020668.
%K A280084 nonn,easy,less
%O A280084 1,2
%A A280084 _Juri-Stepan Gerasimov_, Dec 25 2016