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 A159048 #16 Aug 03 2020 05:38:37 %S A159048 5,7,19,59,109,157,257,439,599,907,1039,1229,1279,1489,1657,3407,3659, %T A159048 4099,5569,6907,7507,7879,8389,9049,10589,11329,11939,14369,16657, %U A159048 17209,17959,18149,18919,19507,20507,22159,26339,30139,31379,34457,36319 %N A159048 Primes of the form m*(m+1)/2 + 4. %H A159048 G. C. Greubel, <a href="/A159048/b159048.txt">Table of n, a(n) for n = 1..1000</a> %e A159048 7=3+4, 19=15+4, 59=55+4, 109=105+4, 157=153+4, 257=253+4, ... %t A159048 Select[Accumulate[Range[500]]+4,PrimeQ] (* _Harvey P. Dale_, Apr 23 2011 *) %o A159048 (PARI) for(n=1, 500, if(isprime(k=n*(n+1)/2 + 4), print1(k, ", "))) \\ _G. C. Greubel_, Jul 03 2017 %Y A159048 Cf. A000217, A055469, A055472, A159047 %K A159048 nonn %O A159048 1,1 %A A159048 _Vladimir Joseph Stephan Orlovsky_, Apr 03 2009 %E A159048 Edited by _N. J. A. Sloane_, Apr 06 2009