A396621 a(n) = r(n,n), where r(1,k)=f(k)=round(k*c), r(n,k)=f(r(n-1,k)), c=Pi.

3, 19, 88, 405, 1549, 5834, 21149, 75866, 265355, 921099, 3283282, 11148271, 37917076, 127640780, 429847793, 1431609343, 4787581515, 16109999609, 53218599589, 175931065354, 577552793980, 1904106332246, 6227990177736, 20417955689954, 67413157001238

Offset

1,1

Comments

a(n + 1)/a(n) approaches c erratically.

Links

Table of n, a(n) for n=1..25.

Mathematica

c = Pi; f[k_] := f[k] = Round[c*k];
r[1, k_] := f[k]; r[n_, k_] := r[n, k] = f[r[n - 1, k]];
Table[r[n, n], {n, 1, 100}]

Crossrefs

Cf. A396385, A396619, A396620.

Sequence in context: A089621 A204256 A015528 * A183384 A050863 A376836

Adjacent sequences: A396618 A396619 A396620 * A396622 A396623 A396624

Keyword

nonn,new

Author

Clark Kimberling, Jun 03 2026

Status

approved