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 A077679 #19 Oct 10 2018 15:15:45 %S A077679 3,30,31,33,34,35,37,38,39,301,302,303,305,307,309,310,311,313,314, %T A077679 317,318,319,321,322,323,326,327,329,330,331,334,335,337,339,341,345, %U A077679 346,347,349,353,354,355,357,358,359,362,365,366,367,370,371,373,374,377 %N A077679 Squarefree numbers beginning with 3. %C A077679 Intersection of A005117 and A217395. - _Michel Marcus_, Sep 14 2013 %C A077679 Lower density is 1/(5*Pi^2), upper density is 5/(3*Pi^2). - _Charles R Greathouse IV_, Nov 05 2017 %H A077679 Harvey P. Dale, <a href="/A077679/b077679.txt">Table of n, a(n) for n = 1..1000</a> %t A077679 Select[Range[400],SquareFreeQ[#]&&IntegerDigits[#][[1]]==3&] (* _Harvey P. Dale_, Oct 10 2018 *) %o A077679 (PARI) isok(n) = (issquarefree(n) && (digits(n, 10)[1] == 3)) \\ _Michel Marcus_, Jul 31 2013 %Y A077679 Cf. A077677, A077678, A077680, A077681, A077682, A077683, A077684, A077685. %K A077679 base,easy,nonn %O A077679 1,1 %A A077679 _Amarnath Murthy_, Nov 16 2002 %E A077679 More terms from _Sascha Kurz_, Jan 28 2003