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 A304441 #12 Oct 08 2019 09:59:44 %S A304441 0,1,2,9,10,18,29,36,45,65,72,73,100,101,136,137,144,153,164,200,208, %T A304441 218,225,234,245,281,288,289,298,324,325,353,416,424,441,450,514,522, %U A304441 541,578,640,648,666,676,738,757 %N A304441 Numbers k such that 8k, 8k+1 and 8k+2 are the sum of two squares; A082982 / 8. %C A304441 Numbers n such that n and n+1 are in the sequence: 0, 1, 9, 72, 100, 136, 288, 324, ...: appear to be in A155562, A140612, and A243180, and in A020684 (except for 1), A034024 & A135571 (except for 0, 1). %F A304441 a(n) = A082982(n) / 8. %o A304441 (PARI) isA001481(n)=my(f=factor(n)); for(i=1, #f[, 1], if(f[i, 2]%2 && f[i, 1]%4==3, return(0))); 1 %o A304441 is(n)=isA001481(n) && isA001481(8*n+1) && isA001481(8*n+2) \\ _Charles R Greathouse IV_, May 17 2018 %Y A304441 Cf. A082982, A155562, A243180, A140612, A020684, A034024, A135571. %K A304441 nonn %O A304441 1,3 %A A304441 _M. F. Hasler_, May 13 2018