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 A306634 #29 Jun 07 2025 08:10:49
%S A306634 0,2755452,4570452,123725995972
%N A306634 Numbers k such that A215339(6*k+2) = 0.
%C A306634 Numbers k such that b(k) is an integer, where b(n) = Sum_{k=0..n} (2*n+k)!/((2*n-2*k)!*(3*k+1)!) (= A001608(6*n+2)/(6*n+2)).
%H A306634 Don Zagier, <a href="https://mathshistory.st-andrews.ac.uk/EMS/Zagier/Problems/">Problems posed at the St Andrews Colloquium, 1996</a>, See "Fifth Day: Sequences and recursions, problem 2".
%e A306634 n | b(n)
%e A306634 --+--------------------------
%e A306634 0 | 1 (= 2/2)
%e A306634 1 | 5/4 (= 10/8)
%e A306634 2 | 51/14
%e A306634 3 | 277/20
%e A306634 4 | 1497/26
%e A306634 5 | 4045/16 (= 8090/32)
%e A306634 6 | 43721/38
%e A306634 7 | 118141/22 (= 236282/44)
%e A306634 8 | 638471/25 (= 1276942/50)
%e A306634 9 | 6900995/56
%Y A306634 Cf. A001608, A013998, A215339.
%K A306634 nonn,more
%O A306634 1,2
%A A306634 _Seiichi Manyama_, Mar 02 2019