A091772 a(n) = gcd(A000108(n), A000110(n)).

1, 2, 5, 1, 2, 1, 1, 10, 1, 1, 2, 1, 1, 2, 5, 1, 6, 7, 1, 4, 3, 3, 2, 3, 37, 34, 47, 5, 68, 53, 11, 2, 1, 39, 14, 1, 1, 2, 1, 1, 4, 1, 77745, 4, 5, 5, 126, 51, 1, 6, 1, 1, 44, 1, 1, 12, 31, 1, 2, 3, 663, 46, 51, 5, 2, 41, 1, 4, 3, 5, 29318, 445, 3, 6, 1, 39, 4, 5, 31, 4, 5, 23, 2, 1

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

Table[GCD[CatalanNumber[n], BellB[n]], {n, 1, 84}] (* Amiram Eldar, Nov 23 2019 *)

Prog

(Python)
from itertools import count, accumulate, islice
def A091772_gen(): # generator of terms
    yield 1
    blist, b, c = (1, 2), 1, 1
    for n in count(1):
        blist = list(accumulate(blist, initial=(b:=blist[-1])))
        yield gcd(b, c := c*(4*n+2)//(n+2))
A091772_list = list(islice(A091772_gen(), 20)) # Chai Wah Wu, Jun 22 2022

Crossrefs

Cf. A000108 (Catalan numbers), A000110 (Bell Numbers).

Sequence in context: A197737 A189824 A197814 * A275479 A075790 A240543

Adjacent sequences: A091769 A091770 A091771 * A091773 A091774 A091775

Keyword

nonn

Author

Jon Perry, Mar 06 2004

Status

approved