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A081390 n-th Catalan number has only one non-unitary prime-divisor; all other prime factors have exponent one. 1
6, 10, 12, 15, 16, 20, 21, 22, 27, 28, 29, 30, 32, 33, 34, 36, 37, 39, 53, 54, 55, 56, 57, 58, 65, 67, 79, 80, 109, 110, 129, 135, 159, 161, 170, 171, 255, 783, 784, 785, 786, 902 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..42.

EXAMPLE

n=902: C(1804,902)/903 has 189 prime factor, 188 stand with exponent one, but 2 with 5: 2^5.

CROSSREFS

Cf. A080664, A000108, A081386-A081389, A080405.

Sequence in context: A134620 A108315 A134616 * A210578 A274426 A324456

Adjacent sequences:  A081387 A081388 A081389 * A081391 A081392 A081393

KEYWORD

nonn

AUTHOR

Labos Elemer, Mar 27 2003

STATUS

approved

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Last modified September 20 07:46 EDT 2020. Contains 337264 sequences. (Running on oeis4.)