A133927 Numbers k such that the sum of the first k Catalan numbers, C_1 + C_2 + ... + C_k, is divisible by k.

1, 30, 494, 6331, 36851, 95450, 122614, 940745, 5126032, 7519204

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, A014138.

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