A354332 a(n) is the numerator of Sum_{k=0..n} (-1)^k / (2*k+1)!.

1, 5, 101, 4241, 305353, 33588829, 209594293, 1100370038249, 23023126954133, 102360822438075317, 42991545423991633141, 4350744396907953273869, 13052233190723859821607001, 9162667699888149594768114701, 7440086172309177470951709137213, 364172638960396581472899447242531

Offset

0,2

Links

Table of n, a(n) for n=0..15.

Formula

Numerators of coefficients in expansion of sin(sqrt(x)) / (sqrt(x) * (1 - x)).

Example

1, 5/6, 101/120, 4241/5040, 305353/362880, 33588829/39916800, 209594293/249080832, ...

Mathematica

Table[Sum[(-1)^k/(2 k + 1)!, {k, 0, n}], {n, 0, 15}] // Numerator
nmax = 15; CoefficientList[Series[Sin[Sqrt[x]]/(Sqrt[x] (1 - x)), {x, 0, nmax}], x] // Numerator

Prog

(PARI) a(n) = numerator(sum(k=0, n, (-1)^k/(2*k+1)!)); \\ Michel Marcus, May 24 2022
(Python)
from fractions import Fraction
from math import factorial
def A354332(n): return sum(Fraction(-1 if k % 2 else 1, factorial(2*k+1)) for k in range(n+1)).numerator # Chai Wah Wu, May 24 2022

Crossrefs

Cf. A009445, A049469, A053557, A061354, A103816, A120265, A143382, A354211, A354298, A354333 (denominators), A354334.

Sequence in context: A041187 A266235 A266452 * A074790 A009757 A119556

Adjacent sequences: A354329 A354330 A354331 * A354333 A354334 A354335

Keyword

nonn,frac

Author

Ilya Gutkovskiy, May 24 2022

Status

approved