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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. 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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 9 03:23 EST 2021. Contains 349625 sequences. (Running on oeis4.)