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 A056061 Number of square divisors of central binomial coefficients. 7
 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, 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, 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 LINKS Michel Marcus, Table of n, a(n) for n = 1..120 FORMULA a(n) = A046951(A001405(n)) = A000005(A000188(A001405(n)). EXAMPLE n=27: binomial(27,1) = 20058300, its largest square-divisor is 900=30^2 so a(27) = tau(30) = 8. MATHEMATICA Table[Count[Divisors@ Binomial[n, Floor[n/2]], d_ /; IntegerQ@ Sqrt@ d], {n, 0, 84}] (* Michael De Vlieger, Feb 18 2017 *) PROG (PARI) a(n) = sumdiv(binomial(n, n\2), d, issquare(d)); \\ Michel Marcus, Feb 19 2017 CROSSREFS Cf. A001405, A046951, A000005, A000188, A056056, A056057, A056058, A056059, A056060. Sequence in context: A166288 A249138 A056648 * A029265 A103648 A127309 Adjacent sequences:  A056058 A056059 A056060 * A056062 A056063 A056064 KEYWORD nonn AUTHOR Labos Elemer Jul 26 2000 STATUS approved

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