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 A056061 #17 Aug 15 2024 03:31:55 %S A056061 1,1,1,1,1,2,1,1,2,4,1,2,2,2,2,2,1,2,1,2,2,2,1,2,4,4,8,8,4,6,2,2,2,4, %T A056061 2,4,4,4,2,4,2,2,2,2,8,12,4,8,8,8,8,8,4,6,2,2,2,3,2,3,3,3,4,4,2,4,2,4, %U A056061 4,4,1,2,2,2,4,4,8,12,2,4,12,12,4,4,8,12,12,12,4,6,8,12,12,12,8,16,8,8,6 %N A056061 Number of square divisors of central binomial coefficients. %H A056061 Michel Marcus, <a href="/A056061/b056061.txt">Table of n, a(n) for n = 1..120</a> %F A056061 a(n) = A046951(A001405(n)) = A000005(A000188(A001405(n))). %e A056061 n=27: binomial(27,13) = 20058300, its largest square-divisor is 900=30^2 so a(27) = tau(30) = 8. %t A056061 Table[Count[Divisors@ Binomial[n, Floor[n/2]], d_ /; IntegerQ@ Sqrt@ d], {n, 0, 84}] (* _Michael De Vlieger_, Feb 18 2017 *) %o A056061 (PARI) a(n) = sumdiv(binomial(n, n\2), d, issquare(d)); \\ _Michel Marcus_, Feb 19 2017 %Y A056061 Cf. A001405, A046951, A000005, A000188, A056056, A056057, A056058, A056059, A056060. %K A056061 nonn %O A056061 1,6 %A A056061 _Labos Elemer_ Jul 26 2000