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 A265402 #15 Dec 13 2015 07:54:55
%S A265402 11,17,23,29,43,47,53,59,67,71,73,83,89,101,103,107,109,113,127,131,
%T A265402 137,149,151,163,167,173,179,191,193,197,223,227,233,239,241,251,257,
%U A265402 263,269,277,281,283,293,311,317,347,349,353,359,373,383,389,397,401,409,419,431,433,443,449,457,461,463,467,479,487,491,503
%N A265402 Fixed points of A265388: numbers n for which gcd{k=1..n-1} binomial(2*n, 2*k) = n.
%H A265402 Antti Karttunen, <a href="/A265402/b265402.txt">Table of n, a(n) for n = 1..1024</a>
%t A265402 Select[Range@ 504, GCD @@ Array[Function[k, Binomial[2 #, 2 k]], {# - 1}] == # &] (* _Michael De Vlieger_, Dec 11 2015 *)
%o A265402 (PARI) isok(n) = (n>1) && gcd(vector(n-1, k, binomial(2*n, 2*k))) == n; \\ _Michel Marcus_, Dec 08 2015, edited by _Antti Karttunen_, Dec 11 2015 (see A265388 for why).
%Y A265402 Fixed points of A265388. Cf. also A265403.
%K A265402 nonn
%O A265402 1,1
%A A265402 _Antti Karttunen_, Dec 08 2015