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 A111909 #9 Dec 06 2015 22:57:41 %S A111909 1,3,4,6,7,8,9,11,12,13,14,15,16,18,19,21,22,23,24,27,28,29,30,31,33, %T A111909 34,35,36,38,39,40,42,43,44,45,46,47,48,49,51,53,54,55,56,57,58,59,60, %U A111909 61,62,63,64,66,67,68,69,70,71,72,73,74,75,76,77,78,79,81,83,84,86,87,88 %N A111909 Numbers that cannot be represented as a^4 + b^2 with a, b > 0. %H A111909 Charles R Greathouse IV, <a href="/A111909/b111909.txt">Table of n, a(n) for n = 1..10000</a> %F A111909 a(n) = n + O(n^(3/4)). - _Charles R Greathouse IV_, Sep 01 2015 %e A111909 3 cannot be represented as a^4 + b^2 and thus is in this sequence while 10 = 1^4 + 3^2 is not. %o A111909 (PARI) list(lim)=lim\=1; my(v=List(),u=vectorsmall(lim),m2); for(m=1,sqrtint(lim-1), m2=m^2; for(n=1,sqrtnint(lim-m2,4), u[m2+n^4]=1)); for(i=1,#u, if(!u[i], listput(v,i))); Set(v) \\ _Charles R Greathouse IV_, Sep 01 2015 %Y A111909 Cf. A111925 (complement), A055394, A022549. A022544 is a subsequence. %K A111909 nonn %O A111909 1,2 %A A111909 _Stefan Steinerberger_, Nov 25 2005