

A133927


Numbers n such that the sum of the first n Catalan numbers, C_1 + C_2 + ... + C_n, is divisible by n.


0




OFFSET

1,2


COMMENTS

The sum of the first 30 Catalan numbers, 1 + 2 + 5 + ... + 3814986502092304 = 5175497420902740, is divisible by 30, so 30 is a term.
No more terms < 5*10^7. [Lars Blomberg, Nov 07 2011]


LINKS

Table of n, a(n) for n=1..10.
Eric Weisstein's World of Mathematics, Catalan Number


CROSSREFS

Cf. A000108.
Sequence in context: A258417 A212473 A127544 * A082556 A036223 A022658
Adjacent sequences: A133924 A133925 A133926 * A133928 A133929 A133930


KEYWORD

hard,more,nonn


AUTHOR

Ryan Propper, Jan 07 2008


STATUS

approved



