OFFSET
1,1
FORMULA
|a(n)-A376457(n)| = 1 for n>=1.
EXAMPLE
For n = 2 the partial sums (of which the 1st is for k=0) are approximately 1, -18.7, 46.2, -39.2, 20.9, -5.4, ..., where the least, -39.2..., is the 4th, so that a(2) = 3.
MATHEMATICA
z = 200; r = Pi;
f[n_, m_] := f[n, m] = N[Sum[(-1)^k (2 n r)^(2 k)/(2 k)!, {k, 0, m}], 10]
t[n_] := Table[f[n, m], {m, 1, z}]
g[n_] := Select[Range[z], f[n, #] == Max[t[n]] &]
h[n_] := Select[Range[z], f[n, #] == Min[t[n]] &]
Flatten[Table[g[n], {n, 1, 60}]] (* A376456 *)
Flatten[Table[h[n], {n, 1, 60}]] (* this sequence *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Oct 01 2024
STATUS
approved