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A255132 Number of divisors of odd Catalan numbers (A038003). 2
1, 1, 2, 8, 96, 2048, 3145728, 206158430208, 27670116110564327424, 498460498419343452338927647605129216, 24991100464315816765228594460089760794425300959309994174606999552, 336610107623104398583024455855523763248864803845734108839073897168302318415095310965480469919661369165797247714066432 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
FORMULA
a(n) = A000005(A038003(n)).
EXAMPLE
A038003(4) = 9694845 which has 96 divisors.
PROG
(Python)
from operator import mul
from functools import reduce
from sympy import factorint
A255132_list, c, s = [1, 1], {}, 3
for n in range(2, 2**15):
....for p, e in factorint(4*n-2).items():
........if p in c:
............c[p] += e
........else:
............c[p] = e
....for p, e in factorint(n+1).items():
........if c[p] == e:
............del c[p]
........else:
............c[p] -= e
....if n == s:
........c2 = reduce(mul, [e+1 for e in c.values()])
........A255132_list.append(c2)
........s = 2*s+1
CROSSREFS
Sequence in context: A087540 A052713 A136797 * A297332 A009752 A322736
KEYWORD
nonn
AUTHOR
Chai Wah Wu, Feb 15 2015
STATUS
approved

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Last modified March 18 22:29 EDT 2024. Contains 370951 sequences. (Running on oeis4.)