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 A081766 #12 May 08 2022 08:47:38 %S A081766 0,1,3,8,13,17,30,46,47,68,73,75,93,98,105,112,122,144,155,172,183, %T A081766 189,192,203,217,233,237,242,254,266,268,269,278,286,294,348,380,401, %U A081766 403,411,423,437,439,443,456,463,476,483,489,494,498,511,520,526,540,563 %N A081766 Numbers k such that k^2+1 divides C(2k,k). %H A081766 Amiram Eldar, <a href="/A081766/b081766.txt">Table of n, a(n) for n = 1..10000</a> %t A081766 Select[Range[0, 600], Divisible[Binomial[2*#, #], #^2 + 1] &] (* _Amiram Eldar_, May 08 2022 *) %Y A081766 Cf. A000984, A002522. %K A081766 easy,nonn %O A081766 1,3 %A A081766 _Benoit Cloitre_, Apr 09 2003 %E A081766 a(1) = 0 inserted by _Amiram Eldar_, May 08 2022