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 A098828 #29 Feb 26 2025 11:36:42
%S A098828 3,11,23,59,83,179,263,311,419,479,683,839,1103,1511,2111,2243,2663,
%T A098828 2963,3119,4139,4703,5099,5303,5939,7079,10223,11399,12011,12323,
%U A098828 12959,17483,19403,21011,21839,22259,24419,25763,27143,27611,28559,30011
%N A098828 Primes of the form 2*n^2 + 2*n - 1.
%C A098828 a(n)==3 (mod 4).
%C A098828 Equivalently primes p such that 2p+3 is square.
%C A098828 Also 3 followed by primes p of the form 2*n^2+6*n+3 = 2*(n+2)^2-2*(n+2)-1 (see the first comment) such that 2^(p-1)+3 is not prime. - _Vincenzo Librandi_, Jan 03 2009; _M. F. Hasler_, Jan 07 2009; _R. J. Mathar_, Jan 14 2009; _Bruno Berselli_, Sep 23 2013
%H A098828 Vincenzo Librandi, <a href="/A098828/b098828.txt">Table of n, a(n) for n = 1..1000</a>
%F A098828 a(n) = (A109367(n) - 3)/2.
%t A098828 Select[Table[Prime[n], {n, 3500}], IntegerQ[(2# + 3)^(1/2)] &] (* _Ray Chandler_, Oct 26 2004 *)
%o A098828 (Magma) [3] cat [ p: p in PrimesUpTo(30100) | exists(t){ n: n in [1..Isqrt(p div 2)] | 2*n^2+6*n+3 eq p } and not IsPrime(2^(p-1)+3) ];
%o A098828 (PARI) list(lim)=my(v=List()); for(n=1,oo, my(t=2*n*(n+1)-1); if(t>lim, return(Vec(v))); if(isprime(t), listput(v,t))) \\ _Charles R Greathouse IV_, Feb 26 2025
%Y A098828 Cf. A109358, A109367, A153238
%K A098828 nonn
%O A098828 1,1
%A A098828 _Giovanni Teofilatto_, Oct 09 2004
%E A098828 Corrected by _Ray Chandler_, Oct 26 2004
%E A098828 Edited by _N. J. A. Sloane_, Jan 25 2009
%E A098828 Name edited by _Charles R Greathouse IV_, Feb 26 2025