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 A373224 #11 May 30 2024 02:59:43 %S A373224 0,1,2,1,0,5,6,1,0,9,0,11,12,1,0,15,0,17,0,-1,20,-1,-2,23,24,25,0,-1, %T A373224 28,29,0,-1,32,-1,34,-1,36,-1,-2,39,-2,41,-2,43,44,-1,-2,-3,-4,49,50, %U A373224 -3,52,-3,54,-3,56,-3,58,59,-2,61,-2,-3,64,65,-2,67,-2,69,70,-1,-2 %N A373224 Row sums of A373223. %F A373224 a(k) = k - 1 <==> k = 1 or 2 or k term of A080147. In other words: If we index the primes starting at 0 then 0, 1 and the indices of the Pythagorean primes (A002144) are the fixed points of this map. %p A373224 A373224 := n -> local k; add(A373223(n, k), k = 1..n): %p A373224 lprint(seq(A373224(n), n = 1..73)); %o A373224 (PARI) KP(p,q) = kronecker(p,q); %o A373224 T(n,k) = my(p=prime(n), q=prime(k)); KP(p,q) * KP(q,p); %o A373224 a(n) = vecsum(vector(n, k, T(n,k))); \\ _Michel Marcus_, May 30 2024 %Y A373224 Cf. A373223, A373225, A002144, A080147. %K A373224 sign %O A373224 1,3 %A A373224 _Peter Luschny_, May 28 2024