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 A245042 #21 Jun 09 2020 03:07:25 %S A245042 17,73,89,193,337,521,953,1009,1249,1657,2377,2833,3329,3433,4441, %T A245042 4561,5849,6553,7297,8081,8737,9769,11617,12401,12601,13417,15569, %U A245042 16937,17881,18121,20353,21649,27529,28729,29033,30577,33457,35449,36809,46273,49801 %N A245042 Primes of the form (k^2+4)/5. %C A245042 Also equal to primes p such that 5*p-4 is a perfect square. %H A245042 Chai Wah Wu, <a href="/A245042/b245042.txt">Table of n, a(n) for n = 1..1000</a> %t A245042 Select[(Range[500]^2+4)/5,PrimeQ] (* _Harvey P. Dale_, Jul 13 2014 *) %o A245042 (Python) %o A245042 import sympy %o A245042 L = (k**2 + 4 for k in range(10**3)) %o A245042 [n//5 for n in L if n % 5 == 0 and sympy.ntheory.isprime(n//5)] %Y A245042 Cf. A154418. %Y A245042 Cf. A154616, A002327, A066436. %K A245042 nonn %O A245042 1,1 %A A245042 _Chai Wah Wu_, Jul 10 2014