A120622 Numbers n such that the n-th Catalan number C(2n, n)/(n + 1) is divisible by n/2 but not divisible by n.

4, 24, 40, 72, 304, 480, 560, 1032, 1248, 1376, 1440, 1632, 1696, 2128, 2320, 2400, 2576, 2720, 3360, 3520, 4104, 4176, 4240, 4320, 4368, 4704, 4896, 5056, 5280, 5568, 5664, 5824, 6160, 6240, 6592, 6848, 6976, 7200, 7360, 7744, 8064, 8200, 8240, 8272

Offset

1,1

Links

Table of n, a(n) for n=1..44.

Mathematica

fQ[n_] := fQ[n_] := IntegerQ[ Binomial[2n, n]/(n(n + 1)/2)] && !IntegerQ[ Binomial[2n, n]/n]; Select[ Range@8719, fQ@# &]

Crossrefs

Cf. A000108, A000217, A014847, A120623.

Sequence in context: A363218 A048188 A121024 * A031117 A174178 A139245

Adjacent sequences: A120619 A120620 A120621 * A120623 A120624 A120625

Keyword

nonn

Author

Robert G. Wilson v, Jun 19 2006

Extensions

Better description from Joel B. Lewis, Nov 15 2006

Status

approved