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 A253278 #23 May 09 2015 14:51:04
%S A253278 1,2,3,4,8,9,11,16,17,19,27,32,33,43,51,57,59,64,67,73,81,83,89,97,99,
%T A253278 107,113,121,128,129,131,139,146,153,163,171,177,178,179,187,193,201,
%U A253278 209,211,227,233,241,243,249,251,256,267,281,283,289,292,297,307
%N A253278 Congruentfree numbers: positive integers that are not divisible by any congruent number (A003273).
%e A253278 8 is in this sequence because the positive integer 8 is not divisible by any of the first 3 congruent numbers 5, 6, 7.
%o A253278 (PARI) isok(n,v) = {my(k=1); while (v[k] <= n, if (n % v[k] == 0, return (0)); k++;); return (1);}
%o A253278 lista(nn) = {v = readvec("b003273.txt"); for (n=1, nn, if (isok(n, v), print1(n, ", ")););} \\ _Michel Marcus_, May 03 2015
%Y A253278 Cf. A003273, A257604.
%K A253278 nonn
%O A253278 1,2
%A A253278 _Juri-Stepan Gerasimov_, May 02 2015
%E A253278 Corrected by _Michel Marcus_, May 03 2015. Edited by _Wolfdieter Lang_, May 05 2015