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 A073077 #20 Apr 26 2025 03:27:29 %S A073077 1,2,20,110,156,210,220,238,240,312,460,468,483,510,561,600,624,665, %T A073077 684,696,720,744,770,806,812,816,868,936,966,1001,1012,1045,1064,1100, %U A073077 1110,1122,1144,1155,1170,1200,1295,1309,1320,1326,1332,1360,1368,1394,1404 %N A073077 Numbers k that divide C(2k,k) and C(4k,2k). %H A073077 Amiram Eldar, <a href="/A073077/b073077.txt">Table of n, a(n) for n = 1..10000</a> %t A073077 Select[Range[1500], Divisible[Binomial[2*#, #], #] && Divisible[Binomial[4*#, 2*#], #] &] (* _Amiram Eldar_, Apr 26 2025 *) %o A073077 (PARI) isok(n) = !(binomial(2*n, n) % n) && !(binomial(4*n, 2*n) % n); \\ _Michel Marcus_, Nov 28 2013 %Y A073077 Subsequence of A014847. %Y A073077 Cf. A000984, A001448. %K A073077 easy,nonn %O A073077 1,2 %A A073077 _Benoit Cloitre_, Aug 17 2002 %E A073077 More terms from _Michel Marcus_, Nov 28 2013