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 A354331 a(n) is the denominator of Sum_{k=0..n} 1 / (2*k+1)!. 5
 1, 6, 40, 5040, 362880, 13305600, 6227020800, 1307674368000, 513257472000, 121645100408832000, 51090942171709440000, 8617338912961658880000, 15511210043330985984000000, 10888869450418352160768000000, 2947253997913233984847872000000, 1174691236311131831103651840000000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Table of n, a(n) for n=0..15. 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 Cf. A009445, A053556, A061355, A073742, A143383, A289488, A354211 (numerators), A354333, A354335. Sequence in context: A086803 A136382 A096716 * A000611 A043069 A257602 Adjacent sequences: A354328 A354329 A354330 * A354332 A354333 A354334 KEYWORD nonn,frac AUTHOR Ilya Gutkovskiy, May 24 2022 STATUS approved

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Last modified September 12 12:46 EDT 2024. Contains 375851 sequences. (Running on oeis4.)