OFFSET
0,2
FORMULA
Denominators of coefficients in expansion of sinh(sqrt(x)) / (sqrt(x) * (1 - x)).
EXAMPLE
1, 7/6, 47/40, 5923/5040, 426457/362880, 15636757/13305600, 7318002277/6227020800, ...
MATHEMATICA
Table[Sum[1/(2 k + 1)!, {k, 0, n}], {n, 0, 15}] // Denominator
nmax = 15; CoefficientList[Series[Sinh[Sqrt[x]]/(Sqrt[x] (1 - x)), {x, 0, nmax}], x] // Denominator
PROG
(PARI) a(n) = denominator(sum(k=0, n, 1/(2*k+1)!)); \\ Michel Marcus, May 24 2022
(Python)
from fractions import Fraction
from math import factorial
def A354331(n): return sum(Fraction(1, factorial(2*k+1)) for k in range(n+1)).denominator # Chai Wah Wu, May 24 2022
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Ilya Gutkovskiy, May 24 2022
STATUS
approved