A353820 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

A353820

Product_{n>=1} (1 + a(n)*x^n/n!) = 1 + arctan(x).

1, 0, -2, 8, -16, 96, -832, 9344, -27648, 238080, -4228608, 55812096, -398991360, 4930609152, -98606039040, 2440552022016, -17762113880064, 235149341884416, -7331825098948608, 170578782435409920, -2009778629489197056, 38563016760590598144, -1278044473427380666368

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

LINKS

Table of n, a(n) for n=1..23.

MATHEMATICA

nn = 23; f[x_] := Product[(1 + a[n] x^n/n!), {n, 1, nn}]; sol = SolveAlways[0 == Series[f[x] - 1 - ArcTan[x], {x, 0, nn}], x]; Table[a[n], {n, 1, nn}] /. sol // Flatten

CROSSREFS

Cf. A006973, A010050, A137852, A353611, A353818, A353819, A353821.

Sequence in context: A100736 A099888 A249308 * A199043 A046161 A092978

Adjacent sequences: A353817 A353818 A353819 * A353821 A353822 A353823

KEYWORD

sign

AUTHOR

Ilya Gutkovskiy, May 08 2022

STATUS

approved