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 A005082 #23 Jul 12 2017 05:26:38
%S A005082 0,0,3,0,0,3,7,0,3,0,11,3,0,7,3,0,0,3,19,0,10,11,23,3,0,0,3,7,0,3,31,
%T A005082 0,14,0,7,3,0,19,3,0,0,10,43,11,3,23,47,3,7,0,3,0,0,3,11,7,22,0,59,3,
%U A005082 0,31,10,0,0,14,67,0,26,7,71,3,0,0,3,19,18,3,79,0,3,0,83,10,0,43,3,11,0,3,7,23,34,47,19,3,0,7,14,0,0,3,103
%N A005082 Sum of primes = 3 mod 4 dividing n.
%H A005082 Antti Karttunen, <a href="/A005082/b005082.txt">Table of n, a(n) for n = 1..10000</a>
%F A005082 Additive with a(p^e) = p if p = 3 (mod 4), 0 otherwise.
%F A005082 From _Antti Karttunen_, Jul 11 2017: (Start)
%F A005082 a(1) = 0; for n > 1, a(n) = (A079978(A020639(n) mod 4)*A020639(n)) + a(A028234(n)).
%F A005082 a(n) = A008472(n) - A005078(n) - 2*A059841(n).
%F A005082 (End)
%t A005082 Table[Total[Select[Transpose[FactorInteger[n]][[1]],Mod[#,4] == 3&]],{n,80}] (* _Harvey P. Dale_, Jan 18 2015 *)
%t A005082 Array[DivisorSum[#, # &, And[PrimeQ@ #, Mod[#, 4] == 3] &] &, 103] (* _Michael De Vlieger_, Jul 11 2017 *)
%o A005082 (Scheme) (define (A005082 n) (if (= 1 n) 0 (+ (* (A079978 (modulo (A020639 n) 4)) (A020639 n)) (A005082 (A028234 n))))) ;; _Antti Karttunen_, Jul 11 2017
%o A005082 (PARI) a(n) = my(f=factor(n)); sum(k=1, #f~, if (((p=f[k,1])%4) == 3, p)); \\ _Michel Marcus_, Jul 11 2017
%Y A005082 Cf. A005069, A005078, A005083, A005084, A005085, A008472, A059841.
%K A005082 nonn
%O A005082 1,3
%A A005082 _N. J. A. Sloane_
%E A005082 More terms from _Antti Karttunen_, Jul 11 2017