

A120622


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


3



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
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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: A338786 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



