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 A072900 #9 Jul 26 2015 10:09:40 %S A072900 8,12,5,28,44,13,17,76,92,29,124,37,41,172,188,53,236,61,268,284,73, %T A072900 316,332,89,97,101,412,428,109,113,508,524,137,556,149,604,157,652, %U A072900 668,173,716,181,764,193,197,796,844,892,908,229,233,956,241,1004,257,1052 %N A072900 Discriminant of quadratic field Q(sqrt(prime(n))) where prime(n) is the n-th prime. %F A072900 a(n) = if prime(n)=4k+1 then prime(n) else prime(n)*4. %F A072900 a(n) = (3*floor((prime(n) mod 4)/2) + 1)*prime(n). - _Reinhard Zumkeller_, Aug 20 2002 %t A072900 If[Mod[#,4]==1,#,4#]&/@Prime[Range[60]] (* _Harvey P. Dale_, Jul 26 2015 *) %o A072900 (PARI) a(n)=if(n<0,0,coredisc(prime(n))) %Y A072900 a(n) = A037449(A000040(n)). %K A072900 easy,nonn %O A072900 1,1 %A A072900 _Benoit Cloitre_, Aug 10 2002